High pressure pump

ABSTRACT

A high pressure pump. The pump comprises a fluid end assembly supported on a power end assembly. The power end assembly is modular and held together by a first set of stay rods. The fluid end assembly comprises a plurality of fluid end sections positioned in a side-by-side relationship. Each fluid end section comprises a housing made of multiple-piece construction. One or more pieces of the housing are configured to having a second set of stay rods attached thereto. The second set of stay rods interconnect the fluid end assembly and a power end assembly and a vertically offset from the first set of stay rods.

RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 17/550,453, authored by Foster et al., and filed on Dec. 14,2021, the entire contents of which are incorporated herein by reference.This application is a Continuation-in-Part of U.S. patent applicationSer. No. 17/825,173, authored by Nowell et al., and filed on May 26,2022, the entire contents of which are incorporated herein by reference.This application also claims the benefit of the following U.S.provisional patent applications: Ser. No. 63/233,241, authored by Fosteret al, and filed on Aug. 14, 2021; Ser. No. 63/235,251, authored byFoster et al., and filed on Aug. 20, 2021; Ser. No. 63/240,889, authoredby Foster et al., and filed on Sep. 4, 2021; Ser. No. 63/246,099,authored by Foster et al., and filed on Sep. 20, 2021; Ser. No.63/301,524, authored by Foster et al., and filed on Jan. 21, 2022; Ser.No. 63/304,070, authored by Foster et al., and filed on Jan. 28, 2022;Ser. No. 63/310,269, authored by Foster et al., and filed on Feb. 15,2022; and Ser. No. 63/312,541, authored by Foster et al., and filed onFeb. 22, 2022. The entire contents of all of the above listedprovisional patent applications are incorporated herein by reference.

BACKGROUND

Various industrial applications may require the delivery of high volumesof highly pressurized fluids. For example, hydraulic fracturing(commonly referred to as “fracking”) is a well stimulation techniqueused in oil and gas production, in which highly pressurized fluid isinjected into a cased wellbore. As shown for example in FIG. 1 , thepressured fluid flows through perforations 10 in a casing 12 and createsfractures 14 in deep rock formations 16. Pressurized fluid is deliveredto the casing 12 through a wellhead 18 supported on the ground surface20. Sand or other small particles (commonly referred to as “proppants”)are normally delivered with the fluid into the rock formations 16. Theproppants help hold the fractures 14 open after the fluid is withdrawn.The resulting fractures 14 facilitate the extraction of oil, gas, brine,or other fluid trapped within the rock formations 16.

Fluid ends are devices used in conjunction with a power source topressurize the fluid used during hydraulic fracturing operations. Asingle fracking operation may require the use of two or more fluid endsat one time. For example, six fluid ends 22 are shown operating at awellsite 24 in FIG. 2 . Each of the fluid ends 22 is attached to a powerend 26 in a one-to-one relationship. The power end 26 serves as anengine or motor for the fluid end 22. Together, the fluid end 22 andpower end 26 function as a high pressure pump.

Continuing with FIG. 2 , a single fluid end 22 and its correspondingpower end 26 are typically positioned on a truck bed 28 at the wellsite24 so that they may be easily moved, as needed. The fluid and proppantmixture to be pressurized is normally held in large tanks 30 at thewellsite 24. An intake piping system 32 delivers the fluid and proppantmixture from the tanks 30 to each fluid end 22. A discharge pipingsystem 33 transfers the pressurized fluid from each fluid end 22 to thewellhead 18, where it is delivered into the casing 12 shown in FIG. 1 .

Fluid ends operate under notoriously extreme conditions, enduring thesame pressures, vibrations, and abrasives that are needed to fracturethe deep rock formations 16, shown in FIG. 1 . Fluid ends may operate atpressures of 5,000-15,000 pounds per square inch (psi) or greater. Fluidused in hydraulic fracturing operations is typically pumped through thefluid end at a pressure of at least 8,000 psi, and more typicallybetween 10,000 and 15,000 psi. However, the pressure may reach up to22,500 psi.

The power end used with the fluid end typically has a power output of atleast 2,250 horsepower during hydraulic fracturing operations. A singlefluid end typically produces a fluid volume of about 400 gallons, or 10barrels, per minute during a fracking operation. A single fluid end mayoperate in flow ranges from 170 to 630 gallons per minute, orapproximately 4 to 15 barrels per minute. When a plurality of fluid endsare used together, the fluid ends collectively may deliver as much as4,200 gallons per minute or 100 barrels per minute to the wellbore.

High operational pressures may cause a fluid end to expand or crack.Such a structural failure may lead to fluid leakage, which leaves thefluid end unable to produce and maintain adequate fluid pressures.Moreover, if proppants are included in the pressurized fluid, thoseproppants may cause erosion at weak points within the fluid end,resulting in additional failures. Likewise, high operational pressuresmay cause damage to the power end over time.

It is not uncommon for conventional fluid ends to experience failureafter only several hundred operating hours. Yet, a single frackingoperation may require as many as fifty (50) hours of fluid endoperation. Thus, a traditional fluid end may require replacement afteruse on as few as two fracking jobs. There is a need in the industry fora high pressure pump configured to avoid or significantly delay thestructures or conditions that cause wear or failures during operation.

BRIEF DESCRIPTION OF THE DRAWINGS

Fluid End Assembly

FIG. 1 is an illustration of the underground environment of a hydraulicfracturing operation.

FIG. 2 illustrates above-ground equipment used in a hydraulic fracturingoperation.

FIG. 3 is a font perspective view of one embodiment of a high pressurepump disclosed herein.

FIG. 4 is a front perspective view of the fluid end assembly shown inFIG. 3 attached to a plurality of stay rods.

FIG. 5 is a rear perspective view of the fluid end assembly and stayrods shown in FIG. 4 .

FIG. 6 is a front elevational view of the fluid end assembly and stayrods shown in FIG. 4 .

FIG. 7 is a front perspective view of the fluid end assembly shown inFIGS. 3 and 4 .

FIG. 8 is a rear perspective view of the fluid end assembly shown inFIG. 7 .

FIG. 9 is a cross-sectional view of one of the fluid end sections makingup the fluid end assembly shown in FIG. 6 , taken along lines A-A.

FIG. 10 is a front perspective view of one of the housings used with oneof the fluid end sections shown in FIG. 7 .

FIG. 11 is a rear perspective view of the housing shown in FIG. 10 .

FIG. 12 is a front elevational view of the housing shown in FIG. 10 .

FIG. 13 is a rear elevational view of the housing shown in FIG. 10 .

FIG. 14 is a cross-sectional view of the housing shown in FIG. 13 ,taken along line B-B.

FIG. 15 is a cross-sectional view of the housing shown in FIG. 13 ,taken along line C-C.

FIG. 16 is a cross-sectional view of the housing shown in FIG. 13 ,taken along line D-D.

FIG. 17 is a front perspective view of the first section of the housingshown in FIG. 10 .

FIG. 18 is a rear perspective view of the first section shown in FIG. 17.

FIG. 19 is a front perspective view of the first section shown in FIG.17 , but the first section has a plurality of stay rods attachedthereto.

FIG. 20 is a rear perspective view of the first section and stay rodsshown in FIG. 19 .

FIG. 21 is a cross-sectional view of the first section and stay rodsshown in FIG. 19 , taken along line E-E.

FIG. 22 is an enlarged view of area F shown in FIG. 21 .

FIG. 23 is a front perspective view of a second section of the housingshown in FIG. 10 .

FIG. 24 is a rear perspective view of the second section shown in FIG.23 .

FIG. 25 is a front perspective view of the third section of the housingshown in FIG. 10 .

FIG. 26 is a rear perspective view of the third section shown in FIG. 25.

FIG. 27 is a front perspective and exploded view of the housing shown inFIG. 10 .

FIG. 28 is a rear perspective and exploded view of the housing shown inFIG. 10 .

FIG. 29 is a cross-sectional view of the fluid end assembly shown inFIG. 6 , taken along line G-G.

FIG. 30 is a rear perspective view of the retention plate shown in FIGS.9 and 29 .

FIG. 31 is a front perspective view of the retention plate shown in FIG.30 .

FIG. 32 is a rear perspective view of the retention plate shown in FIG.30 attached to the housing shown in FIG. 10 .

FIG. 33 is a front perspective view of the stuffing box shown in FIGS. 9and 29 .

FIG. 34 is a rear perspective view of the stuffing box shown in FIG. 33.

FIG. 35 is a front perspective view of the rear retainer shown in FIGS.9 and 29 .

FIG. 36 is a rear perspective view of the rear retainer shown in FIG. 35.

FIG. 37 is a front perspective view of the packing nut shown in FIGS. 9and 29 .

FIG. 38 is a rear perspective view of the packing nut shown in FIG. 37 .

FIG. 39 is an enlarged cross-sectional view of the components attachedto a rear surface of the housing in FIG. 9 .

FIG. 40 is the cross-sectional view of the fluid end assembly shown inFIG. 9 . The plunger is retracted, and the discharge valve is shown in aclosed position.

FIG. 41 is the cross-sectional view of the fluid end assembly shown inFIG. 40 , but the plunger is extended within the fluid end section andthe suction valve is in a closed position.

FIG. 42 is an enlarged view of area I shown in FIG. 41 .

FIG. 43 is a front perspective view of the fluid routing plug shown inFIGS. 40 and 41 .

FIG. 44 is a side elevational view of the fluid routing plug shown inFIG. 43 .

FIG. 45 is a front elevational view of the fluid routing plug shown inFIG. 43 .

FIG. 46 is a rear perspective view of the fluid routing plug shown inFIG. 43 .

FIG. 47 is a rear elevational view of the fluid routing plug shown inFIG. 43 .

FIG. 48 is a cross-sectional view of the fluid routing plug shown inFIG. 47 , taken along line J-J.

FIG. 49 is a top perspective view of the fluid routing plug shown inFIG. 43 .

FIG. 50 is an enlarged view of area K shown in FIG. 49 .

FIG. 51 is a perspective cross-sectional view of the fluid routing plugshown in FIG. 44 , taken along line L-L.

FIG. 52 is a perspective cross-sectional view of the fluid routing plugshown in FIG. 44 , taken along line M-M.

FIG. 53 is a perspective cross-sectional view of the fluid routing plugshown in FIG. 44 , taken along line N-N.

FIG. 54 is a rear elevational view of the fluid routing plug shown inFIG. 43 , but one of the suction passages and one of the dischargepassages are shown in phantom.

FIG. 55 is a cross-sectional view of the fluid routing plug shown inFIG. 44 , taken along line M-M.

FIG. 56 is a front elevational and conical-sectional view of the fluidrouting plug shown in FIG. 43 . The conical-section is taken from line Oin FIGS. 43 and 45 to line P in FIGS. 46 and 47 .

FIG. 57 is a front perspective and conical-sectional view of the fluidrouting plug shown in FIG. 56 .

FIG. 58 is a rear perspective and conical-sectional view of the fluidrouting plug shown in FIG. 56 .

FIG. 59 is a side elevational and conical-sectional view of the fluidrouting plug shown in FIG. 56 .

FIG. 60 is a side elevational view of the hardened insert shown in FIGS.40 and 41 .

FIG. 61 is a front perspective view of the hardened insert shown in FIG.60 .

FIG. 62 is a front elevational view of the hardened insert shown in FIG.60 .

FIG. 63 is a cross-sectional view of the hardened insert shown in FIG.62 , taken along line Q-Q.

FIG. 64 is a front perspective view of the discharge valve shown inFIGS. 40 and 41 .

FIG. 65 is a rear perspective view of the discharge valve shown in FIG.64 .

FIG. 66 is a side elevational view of the discharge valve shown in FIG.64 .

FIG. 67 is a cross-sectional view of the discharge valve shown in FIG.66 , taken along line R-R.

FIG. 68 is a front perspective view of the suction valve guide shown inFIGS. 40 and 41 .

FIG. 69 is a rear perspective view of the suction valve guide shown inFIG. 68 .

FIG. 70 is a front elevational view of the suction valve guide shown inFIG. 68 .

FIG. 71 is a cross-sectional view of the suction valve guide shown inFIG. 70 , taken along line S-S.

FIG. 72 is a front perspective view of the discharge plug shown in FIGS.40 and 41 .

FIG. 73 is a rear perspective view of the discharge plug shown in FIG.72 .

FIG. 74 is a front elevational view of the discharge plug shown in FIG.72 .

FIG. 75 is a cross-sectional view of the discharge plug shown in FIG. 74, taken along line T-T.

FIG. 76 is a front perspective view of the front retainer shown in FIGS.40 and 41 .

FIG. 77 is a rear perspective view of the front retainer shown in FIG.76 .

FIG. 78 is an enlarged view of area U shown in FIG. 41 .

FIG. 79 is a front perspective and exploded view of the fluid endsection shown in FIGS. 9, 29, 40, and 41 .

FIG. 80 is a rear perspective and exploded view of the fluid end sectionshown in FIGS. 9, 29, 40, and 41 .

Power End Assembly

FIG. 81 is a front elevational view of the high pressure pump shown inFIG. 3 .

FIG. 82 is a cross-sectional view of the high pressure pump shown inFIG. 81 , taken along line W-W.

FIG. 83 is a cross-sectional view of the high pressure pump shown inFIG. 81 , taken along line X-X.

FIG. 84 is a cross-sectional view of the high pressure pump shown inFIG. 81 , taken along line Y-Y.

FIG. 85 is a front perspective view of the power end assembly shown inFIG. 3 .

FIG. 86 is the front perspective view of the power end assembly shown inFIG. 85 , but the base section, engine section, second stay rods, andlubrication system have been removed for clarity.

FIG. 87 is a front perspective view of the crank frame shown in FIG. 86.

FIG. 88 is an enlarged and exploded view of area Z shown in FIG. 130 .

FIG. 89 is a rear perspective view of the crank frame shown in FIG. 87 .

FIG. 90 is a front elevational view of the crank frame shown in FIG. 87.

FIG. 91 is a cross-sectional view of the crank frame shown in FIG. 90 ,taken along line AA-AA.

FIG. 92 is a cross-sectional view of the crank frame shown in FIG. 90 ,taken along line AB-AB.

FIG. 93 is a cross-sectional view of the crank frame shown in FIG. 90 ,taken along line AC-AC.

FIG. 94 is a front perspective view of the crank frame shown in FIG. 87with a plurality of roller bearings installed therein. A section of theframe has been cut-away to expose the interior of the frame.

FIG. 95 is the front perspective and sectional view of the crank frameshown in FIG. 94 with the crankshaft installed therein.

FIG. 96 is a first side perspective view of the crankshaft shown in FIG.95 .

FIG. 97 is a second side perspective view of the crankshaft shown inFIG. 96 .

FIG. 98 is a front elevational view of the crankshaft shown in FIG. 96 .

FIG. 99 is the front elevational view of the crankshaft shown in FIG. 96with the inner lube ports shown in phantom.

FIG. 100 is a rear perspective view of the crank section shown in FIG.86 .

FIG. 101 is a front elevational view of one of the crosshead guidesshown in FIG. 86 .

FIG. 102 is a front perspective view of the crosshead guide shown inFIG. 101 .

FIG. 103 is a rear elevational view of the crosshead guide shown in FIG.101 .

FIG. 104 is a rear perspective view of the crosshead guide shown in FIG.103 .

FIG. 105 is a cross-sectional view of the crosshead guide shown in FIG.101 , taken along line AD-AD.

FIG. 106 is a cross-sectional view of the crosshead guide shown in FIG.101 , taken along line AE-AE.

FIG. 107 is a cross-sectional view of the crosshead guide shown in FIG.101 , taken along line AF-AF.

FIG. 108 is a cross-sectional view of the crosshead guide shown in FIG.103 , taken along line AG-AG.

FIG. 109 is an enlarged view of area AH shown in FIG. 130 . The enlargedview depicts a rear perspective and exploded view of the crosshead guideshown in FIG. 101 having a plurality of second stay rods installedtherein.

FIG. 110 is a front elevational view of the power end assembly shown inFIG. 86 .

FIG. 111 is a cross-sectional view of the power end assembly shown inFIG. 110 , taken along line AI-AI.

FIG. 112 is a cross-sectional view of the power end assembly shown inFIG. 110 , taken along line AJ-AJ.

FIG. 113 is a cross-sectional view of the power end assembly shown inFIG. 85 , taken along line AK-AK.

FIG. 114 is a front elevational view of the crosshead shown installedwithin the power end assembly in FIGS. 111-113 .

FIG. 115 is a front perspective view of the crosshead shown in FIG. 114.

FIG. 116 is a side elevational view of the crosshead shown in FIG. 114 .

FIG. 117 is a cross-sectional view of the crosshead shown in FIG. 114 ,taken along line AL-AL.

FIG. 118 is a front perspective view of the wrist pin shown installedwithin the crosshead in FIGS. 111-113 .

FIG. 119 is a front elevational view of the wrist pin shown in FIG. 118.

FIG. 120 is a cross-sectional view of the wrist pin shown in FIG. 119 ,taken along line AM-AM.

FIG. 121 is a front perspective and exploded view of the pony rod,crosshead, and connecting arm shown installed within the power endassembly in FIGS. 111-113 .

FIG. 122 is a rear perspective and exploded view of the pony rod,crosshead, and connecting arm shown in FIG. 121 .

FIG. 123 is a front perspective and assembled view of the pony rod,crosshead, and connecting arm shown in FIG. 121 .

FIG. 124 is a front perspective view of the pony rod seal plate shownattached to the power end assembly in FIGS. 111-113 .

FIG. 125 is a rear perspective view of the pony rod seal plate shown inFIG. 124 .

FIG. 126 is a front elevational view of the pony rod seal plate shown inFIG. 124 .

FIG. 127 is a cross-sectional view of the pony rod seal plate shown inFIG. 126 , taken along line AN-AN.

FIG. 128 is a front perspective and exploded view of the pony rod sealplate shown in FIG. 124 .

FIG. 129 is a front perspective view of the central support plateincluded in the power end assembly shown in FIGS. 111-113 .

FIG. 130 is a rear perspective and partially exploded view of the powerend assembly shown in FIG. 86 . A portion of the crosshead section andcorresponding second stay rods of the power end assembly have beenremoved for clarity.

FIG. 131 is a rear perspective view of the rear support plate includedin the power end assembly shown in FIGS. 111-113 .

FIG. 132 is a front perspective view of the upper front support plateincluded in the power end assembly shown in FIGS. 111-113 .

FIG. 133 is a front perspective view of the lower front support plateincluded in the power end assembly shown in FIGS. 111-113 .

FIG. 134 is a front perspective and partially exploded view of the powerend assembly shown in FIG. 86 .

FIG. 135 is the front perspective view and exploded view of the powerend assembly shown in FIG. 134 , but more components are shown explodedfrom the assembly.

FIG. 136 is an enlarged view of area AO shown in FIG. 112 .

FIG. 137 is an enlarged view of area AP shown in FIG. 112 .

FIG. 138 is a front perspective view of the power end assembly shown inFIG. 85 , but the engine section and second stay rods have been removedfor clarity.

FIG. 139 is a front perspective and exploded view of the power endassembly shown in FIG. 138 .

FIG. 140 is a cross-sectional view of the power end assembly shown inFIG. 138 , taken along line AQ-AQ.

FIG. 141 is an enlarged view of area AR shown in FIG. 140 .

DETAILED DESCRIPTION

Turning now to FIG. 3 , a high pressure pump 50 disclosed herein isshown. The pump 50 comprises a fluid end assembly 52 joined to a powerend assembly 54. The fluid end assembly 52 is described with referenceto FIGS. 4-80 and the power end assembly 54 is described with referenceto FIGS. 81-141 .

Fluid End Assembly

Turning to FIGS. 4-8 , the fluid end assembly 52 comprises a pluralityof fluid end sections 56 positioned in a side-by-side relationship, asshown in FIGS. 6-8 . Each fluid end section 56 is attached to the powerend assembly 54 using a plurality of stay rods 58, as shown in FIGS. 4and 5 . Preferably, the fluid end assembly 52 comprises five fluid endsections 56 positioned adjacent one another. In alternative embodiments,the fluid end assembly 52 may comprise more or less than five fluid endsections 56. In operation, a single fluid end section 56 may be removedand replaced without removing the other fluid end sections 56 from thefluid end assembly 52.

Housing of Fluid End Section

Turning to FIGS. 10-16 , each fluid end section 56 comprises ahorizontally positioned housing 60 having a longitudinal axis 62extending therethrough, as shown in FIGS. 10 and 11 . The housing 60 hasopposed front and rear surfaces 64 and 66 joined by an outerintermediate surface 68. A horizontal bore 70 is formed within thehousing 60 and interconnects the front and rear surfaces 64 and 66, asshown in FIGS. 14 and 15 . The horizontal bore 70 is sized to receivevarious components configured to route fluid throughout the housing 60,as shown in FIG. 9 . The various components will be described in moredetail later herein.

Continuing with FIGS. 10-16 , the housing 60 is of multi-piececonstruction. The housing 60 comprises a first section 72 joined to asecond section 74 and a third section 76 by a plurality of firstfasteners 78, as shown in FIGS. 15 and 16 . By making the housing 60 outof multiple pieces rather than a single, integral piece, any one of thesections 72, 74, and 76 may be removed and replaced with a new section72, 74, and 76, without replacing the other sections. For example, if aportion of the second section 74 begins to erode or crack, the secondsection 74 can be replaced without having to replace the first or thirdsections 72 and 76. In contrast, if the housing 60 were one singlepiece, the entire housing would need to be replaced, resulting in muchmore costly repair to the fluid end assembly 52.

First Section of Housing

Turning to FIGS. 17-21 , the first section 72 is positioned at the frontend of the housing 60 and includes the front surface 64. Duringoperation, fluid within the first section 72 remains at relatively thesame high pressure. Thus, the first section 72 is considered the staticor constant high pressure section of the housing 60. The first section72 is configured to be attached to a plurality of the stay rods 58, asshown in FIGS. 19-21 . Thus, each fluid end section 56 is attached tothe power end assembly 54 via the first section 72 of the housing 60.

Continuing with FIGS. 17 and 18 , each first section 72 comprises thefront surface 64 joined to a rear surface 80. The surfaces 64 and 80 areinterconnected by a portion of the outer intermediate surface 68 and aportion of the horizontal bore 70. The outer intermediate surface 68 ofthe first section has the shape of a rectangular prism with a pluralityof notches 82 formed within the front surface 64. A notch 82 is formedwithin each corner of the first section 72 such that the front surface64 has a cross-sectional shape of a cross sign having radiused corners.The notches 82 are configured to receive a first end 84 of each stay rod58, as shown in FIG. 21 .

With reference to FIGS. 17-21 , a plurality of passages 86 are formed inthe first section 72. Each passage 86 interconnects the rear surface 80and a medial surface 88 of the first section 72. The medial surface 88is defined by the plurality of notches 82. Each passage 86 comprises acounterbore 87 that opens on the rear surface 80, as shown in FIG. 16 ,and is configured to receive a corresponding one of the stay rods 58.When installed within the first section 72, the first end 84 of eachstay rod 58 projects from the medial surface 88 and into thecorresponding notch 82, as shown in FIG. 21 .

Continuing with FIGS. 19-21 , a threaded fastener 90 is installed on thefirst end 84 of each stay rod 58 within each notch 82. The fastener 90is a three-piece nut, also known as a torque nut, that facilitates theapplication of high torque required to properly fasten the fluid endsection 56 to the power end assembly 54. The fastener 90 is identical tothe three-piece fastener 904 described with reference to FIG. 137herein. In alternative embodiments, a traditional 12-point flange nutsimilar to the flange nut 230, shown in FIGS. 27 and 28 , may beinstalled on the first end 84 of each stay rod 58 instead of thefastener 90.

Continuing with FIGS. 19-22 , a sleeve 94 is disposed around a portionof each stay rod 58 and extends between the rear surface 80 of the firstsection 72 and the power end assembly 54, as shown in FIG. 3 . A dowelsleeve 93 is inserted into each counterbore 87 formed in each passage86, as shown in FIG. 22 . When installed therein, a portion of the dowelsleeve 93 projects from the rear surface 80 of the first section 72. Acounterbore 95 is formed within the hollow interior of the sleeve 94 forreceiving the projecting end of the dowel sleeve 93, as shown in FIG. 22. The dowel sleeve 93 aligns the sleeve 94 and the passage 86concentrically. Such alignment maintains a planar engagement between therear surface 80 of the first section 72 and the sleeve 94. When thefastener 90 is torqued against the medial surface 88 of the firstsection 72, the sleeve 94 abuts the rear surface 80 of the first section72, rigidly securing the first section 72 to the stay rod 58.

Turning back to FIGS. 14-16, and 18 , a plurality of threaded openings96 are formed in the rear surface 80 of the first section 72. Theopenings 96 surround an opening of the horizontal bore 70, as shown inFIG. 18 . Each opening 96 is configured to receive a corresponding oneof the first fasteners 78 used to secure the sections 72, 74, and 76together, as shown in FIGS. 15 and 16 . A plurality of dowel openings 98are also formed in the rear surface 80 adjacent the openings 96, asshown in FIGS. 14 and 18 . The dowel openings 98 are configured toreceive first alignment dowels 100, as shown in FIG. 14 . The firstalignment dowels 100 assist in properly aligning the first section 72and the second section 74 during assembly of the housing 60.

Continuing with FIG. 14 , a pair of upper and lower discharge bores 102and 104 are formed within the first section 72 and interconnect theintermediate surface 68 and the horizontal bore 70. The upper and lowerdischarge bores 102 and 104 shown in FIG. 14 are collinear. Inalternative embodiments, the bores 102 and 104 may be offset from oneanother and not collinear. Each bore 102 and 104 may include acounterbore 106 that opens on the intermediate surface 68. Eachcounterbore 106 is sized to receive a portion of a discharge fittingadapter 504, as shown in FIG. 9 . The fitting adapter 504 spans betweenthe discharge bore 102 or 104 and a discharge fitting 108 attached tothe outer intermediate surface 68 of the first section 72.

Continuing with FIG. 14 , a groove 110 may be formed in the side wallsof the counterbore 106 for receiving a seal 112. The seal 112 engages anouter surface of the fitting adapter 504 to prevent fluid from leakingbetween the first section 72 and the discharge fitting 108, as shown inFIG. 9 .

With reference to FIGS. 17 and 18 , a plurality of threaded openings 114are formed in the intermediate surface 68 and surrounding the opening ofthe upper and lower discharges bores 102 and 104. The threaded openings114 are configured to receive a plurality of threaded fasteners 116configured to secure a discharge fitting 108 to the first section 72, asshown in FIG. 9 .

Continuing with FIGS. 14 and 15 , the walls surrounding the horizontalbore 70 within the first section 72 and positioned between the frontsurface 64 and the upper and lower discharge bores 102 and 104 are sizedto receive a front retainer 118 and a discharge plug 120, as shown inFIG. 9 . The discharge plug 120 seals fluid from leaking from the frontsurface 64 of the housing 60, and the front retainer 118 secures thedischarge plug 120 within the first section 72 of the housing 60.

Continuing with FIGS. 14 and 15 , internal threads 122 are formed in thewalls of the first section 72 for mating with external threads 124,shown in FIGS. 76 and 77 , formed on an outer surface of the frontretainer 118. In contrast, an outer surface of the discharge plug 120faces flat walls of the first section 72. A small amount of clearancemay exist between the plug 120 and the walls of the first section 72.

Continuing with FIGS. 14 and 15 , a groove 125 may be formed in suchwalls for receiving a seal 126 configured to engage an outer surface ofthe discharge plug 120, as shown in FIG. 9 . The seal 126 prevents fluidfrom leaking around the discharge plug 120 during operation. A locatingcutout 128 may further be formed in the walls that is configured toreceive a locating dowel pin 130. As will be described later herein, thelocating dowel pin 130 is used to properly align the discharge plug 120within the housing 60.

Continuing with FIGS. 14 and 15 , the walls surrounding the horizontalbore 70 and positioned between the upper and lower discharge bores 102and 104 and the rear surface 80 of the first section 72 are sized toreceive a portion of a fluid routing plug 132, as shown in FIG. 9 . Thisarea of the walls surrounding the horizontal bore 70 includes acounterbore 134 that opens on the rear surface 80. The counterbore 134is sized to receive a wear ring 136, as shown in FIG. 9 . The wear ring136 has an annular shape and is configured to engage a first seal 386installed within an outer surface of the fluid routing plug 132, asshown in FIG. 9 . In alternative embodiments, the first section 72 maynot include the counterbore 134 or the wear ring 136 and instead may besized to directly engage the first seal 386 installed within the fluidrouting plug 132.

Continuing with FIG. 9 , in addition to the above mentioned components,the first section 72 is also configured to house a discharge valve 138.The components discussed above and installed within the first section 72will be described in more detail later herein.

Second Section of Housing

Turning to FIGS. 23 and 24 , the second section 74 of the housing 60 isconfigured to be positioned between the first and third sections 72 and76 and has a cylindrical cross-sectional shape. During operation, fluidpressure within the second section 74 remains at relatively the samepressure. The pressure is lower than that within the first section 72.Thus, the second section 74 may be referred to as the static or constantlow pressure section of the housing 60. The second section 74 comprisesopposed front and rear surfaces 140 and 142 joined by a portion of theouter intermediate surface 68 and a portion of the horizontal bore 70.

Continuing with FIGS. 15, 16, 23, and 24 , a plurality of passages 144are formed in the second section 74. The passages 144 surround thehorizontal bore 70 and interconnect the front and rear surfaces 140 and142, as shown in FIGS. 15 and 16 . Each passage 144 is configured toreceive a corresponding one of the first fasteners 78 used to secure thesections 72, 74, and 76 of the housing 60 together.

Continuing with FIGS. 14, 23, and 24 , a plurality of dowel openings 146are formed in the front surface 140 of the second section 74, as shownin FIG. 23 . The dowel openings 146 align with the dowel openings 98formed in the rear surface 80 of the first section 72 and are configuredto receive a portion of the first alignment dowels 100, as shown in FIG.14 . Likewise, a plurality of dowel openings 148 are formed in the rearsurface 142 of the second section 74, as shown in FIG. 24 . The dowelopenings 148 are configured to receive a portion of second alignmentdowels 150, as shown in FIG. 14 . The second alignment dowels 150 areconfigured to align the second section 74 and the third section 76during assembly.

Continuing with FIGS. 14, 15, 23 and 24 , a first annular groove 152 isformed in the front surface 140 of the second section 74 such that itsurrounds an opening of the horizontal bore 70, as shown in FIG. 23 .The first groove 152 is positioned between the horizontal bore 70 andthe plurality of passages 144 and is configured to receive a first seal154, as shown in FIGS. 14 and 15 . Likewise, a second annular groove 156is formed in the rear surface 142 of the second section 74 andpositioned between the horizontal bore 70 and the plurality of passages144, as shown in FIG. 24 . The second groove 156 is configured toreceive a second seal 158, as shown in FIGS. 14 and 15 . The seals 154and 158 shown in FIGS. 14 and 15 are O-rings. The seals 154 and 158prevent fluid from leaking between the first and second sections 72 and74 and between the second and third sections 74 and 76 during operation.

Continuing with FIGS. 14, 23, and 24 , a pair of upper and lower suctionbores 160 and 162 are formed within the second section 74 andinterconnect the intermediate surface 68 and the horizontal bore 70. Theupper and lower suction bores 160 and 162 shown in FIG. 14 arecollinear. In alternative embodiments, the bores 160 and 162 may beoffset from one another and not collinear.

Continuing with FIGS. 9 and 14 , the suction bores 160 and 162 are eachconfigured to receive a suction conduit 166, as shown in FIG. 9 . Thesuction conduit 166 comprises a first connection member 164 configuredto mate with the housing 60. Each suction bore 160 and 162 opens into acounterbore 168 sized to receive a portion of the first connectionmember 164. Internal threads 170 are formed in a portion of the wallssurrounding the counterbore 168 for mating with external threads 172,shown in FIG. 78 , formed on the first connection member 164.

Continuing with FIGS. 9 and 14 , a groove 174 is formed in the wallssurrounding the counterbore 168 and configured to receive a seal 176, asshown in FIG. 9 . The seal 176 engages an outer surface of the firstconnection member 164 to prevent fluid from leaking from the housing 60during operation. The suction conduits 166 will be described in moredetail later herein.

Continuing with FIGS. 9, 14, and 15 , the walls surrounding thehorizontal bore 70 within the second section 74 are configured toreceive a majority of the fluid routing plug 132, as shown in FIG. 9 . Asmall amount of clearance may exist between the walls of the secondsection 74 and an outer surface of the fluid routing plug 132.

Third Section of Housing

Turning to FIGS. 14-16, 25 and 26 , the third section 76 of the housing60 is positioned at the rear end of the housing 60 and includes the rearsurface 66. The third section 76 has a generally cylindricalcross-sectional shape. Fluid pressure within the third section 76 variesduring operation. Thus, the third section 76 may be referred to as thedynamic or variable pressure section of the housing 60.

Continuing with FIGS. 25 and 26 , the third section 76 comprises a frontsurface 178 joined to the rear surface 66 of the housing 60 by a portionof the outer intermediate surface 68 and a portion of the horizontalbore 70. The outer intermediate surface 68 of the third section 76varies in diameter such that the third section 76 comprises a frontportion 180 joined to a rear portion 182.

Continuing with FIGS. 15, 16, 25, and 26 , the front portion 180 has aconstant outer diameter and has a plurality of passages 184 formedtherein. The passages 184 interconnect the front surface 178 and amedial surface 186 of the third section 76. The passages 184 align withthe plurality of passages 144 formed in the second section 74 and thethreaded openings 96 formed in the first section 72 of the housing 60,as shown in FIGS. 14 and 15 . The passages 184 are configured to receivethe first fasteners 78 used to secure the sections 72, 74, and 76together.

Continuing with FIGS. 14 and 25 , a plurality of dowel openings 188 areformed in the front surface 178 of the third section 76, as shown inFIG. 25 . The dowel openings 188 are configured to receive a portion ofsecond alignment dowels 150, as shown in FIG. 14 . The second alignmentdowels 150 are configured to properly align the third section 76 withinthe second section 74 during assembly.

Continuing with FIGS. 25 and 26 , the rear portion 182 of the thirdsection 76 comprises a neck 190 joined to a shoulder 192. The neck 190interconnects the front portion 180 and the shoulder 192. The shoulder192 includes the rear surface 66 of the housing 60. The neck 190 has asmaller outer diameter than that of the front portion 180 and theshoulder 192 to provide clearance for the plurality of passages 184formed in the front portion 180.

With reference to FIGS. 25 and 26 , a plurality of first threadedopenings 194 are formed in the rear surface 66 of the third section 76.The first threaded openings 194 are configured to receive a plurality ofsecond fasteners 196, as shown in FIG. 29 . The second fasteners 196 areconfigured to secure a stuffing box 198 and a rear retainer 200 to thethird section 76 of the housing 60, as shown in FIG. 29 . The stuffingbox 198 and the rear retainer 200 will be described in more detail laterherein.

With reference to FIGS. 26 and 32 , a plurality of second threadedopenings 202 are also formed in the rear surface 66 of the third section76, as shown in FIG. 26 . The second threaded openings 202 areconfigured to receive a plurality of third fasteners 204. The thirdfasteners 204 are configured to secure a retention plate 206 to the rearsurface of the housing 60, as shown in FIG. 32 . The retention plate 206will be described in more detail later herein. A plurality of dowelopenings 207 are also formed in the rear surface of the third section76. The dowel openings 207 are configured to receive third alignmentdowels 242, as shown in FIG. 39 .

Turning back to FIGS. 9, 14, 15, and 25 , a counterbore 208 is formed inthe walls surrounding the horizontal bore 70 within the third section 76and opens on the front surface 178. The counterbore 208 is configured toreceive a hardened insert 210, as shown in FIG. 9 . The insert 210 willbe described in more detail later herein. The insert 210 engagesportions of the fluid routing plug 132 when the fluid routing plug 132is installed within the housing 60, as shown in FIG. 9 . The wallssurrounding the horizontal bore 70 between the counterbore 208 and themedial surface 186 of the third section 76 are further configured toreceive a suction valve guide 212. A suction valve 214 is also installedwithin the third section 76 of the housing 60. The suction valve 214 andsuction valve guide 212 will be described in more detail later herein.

Continuing with FIGS. 9, 14, 15, 25, and 26 , the walls surrounding thehorizontal bore 70 within the neck 190 of the rear portion 182 are sizedto receive at least a portion of a reciprocating plunger 216, as shownin FIG. 9 . The portion of the horizontal bore 70 extending through theneck 190 has a uniform diameter and opens into a first counterbore 218formed in the shoulder 192, as shown in FIGS. 14 and 15 . The firstcounterbore 218 is sized to receive a portion of the stuffing box 198,as shown in FIG. 9 . The first counterbore 218 opens into a secondcounterbore 220, of which opens on the rear surface 66 of the housing60, as shown in FIGS. 14, 15, and 26 . The second counterbore 220 issized to receive a wear ring 222 and a seal 224, as shown in FIG. 9 .The wear ring 222 and the seal 224 each have an annular shape. When suchcomponents are installed within the housing 60, the wear ring 222surrounds the seal 224, and the seal 224 engages an outer surface of thestuffing box 198.

Assembly of Housing

Turning to FIGS. 27-29 , the housing 60 is assembled by threading afirst end 226 of each of the first fasteners 78 into a corresponding oneof the threaded openings 96 formed in the first section 72. Onceinstalled therein, the first fasteners 78 project from the rear surface80 of the first section 72. The second and third sections 74 and 76 maythen be slid onto the fasteners 78 projecting from the first section 72using the corresponding passages 144 and 184. The first and secondalignment dowels 100 and 150 help to further align the sections 72, 74,and 76 together during assembly.

Continuing with FIGS. 27-29 , when the second and third sections 74 and76 are installed on the fasteners 78, a second end 228 projects from themedial surface 186 of the third section 76, as shown in FIG. 29 . Aflange nut 230 is installed on the second end 228 and torqued againstthe medial surface 186, tightly securing the sections 72, 74, and 76together. When the housing 60 is assembled, a footprint of the rearsurface 142 of the second section 74 is entirely within a footprint ofthe rear surface 80 of the first section 72, as shown in FIG. 29 .

Continuing with FIGS. 27-29 , the first fastener 78 shown in the figuresis a threaded stud. In alternative embodiments, other types of fastenersknown in the art may be used instead of a threaded stud. For example,screws or bolts may be used to secure the sections together. In furtheralternative embodiments, the nut may comprise the three-piece fastener90, shown in FIGS. 19-21 .

Continuing with FIGS. 27-29 , to remove a section 72, 74, or 76, the nut230 is unthreaded from the second end 228 of each first fastener 78. Thesections 72, 74, and 76 may then be pulled apart, as needed. If thefirst section 72 is being replaced, the first fasteners 78 are alsounthreaded from the threaded openings 96. The components installedwithin the housing 60 may also be removed, as needed, prior todisassembling the housing 60.

Components Attached to Rear Surface of Housing

Turning to FIGS. 29-32 , in addition to the housing 60, the fluid endsection 56 comprises a plurality of components attached to the rearsurface 66 of the housing 60. Such components are configured to receivethe plunger 216. The various components include the retention plate 206,the stuffing box 198, and the rear retainer 200, previously mentioned.The components further comprise a plunger packing 300, and a packing nut290.

Retention Plate

Continuing with FIGS. 29-32 , the retention plate 206 has a cylindricalcross-sectional shape and is sized to cover the rear surface 66 of thehousing 60 and the wear ring 222 and the seal 224, as shown in FIG. 29 .The retention plate 206 holds the wear ring 222 and the seal 224 withinthe housing 60 in the event the stuffing box 198 needs to be removed.

Continuing with FIGS. 29-32 , the retention plate 206 comprises opposedfront and rear surface 237 and 238 joined by a central opening 239formed therein. A plurality of first passages 234 are formed in theretention plate 206 and surround the central opening 239 of the plate206. The first passages 234 align with the first threaded openings 194formed in the rear surface 66 of the housing 60 and are configured toreceive the plurality of second fasteners 196.

Continuing with FIGS. 30-32 , a plurality of second passages 236 arealso formed in the retention plate 206. The second passages 236 alignwith the second threaded openings 202 formed in the rear surface 66 ofthe housing 60 and are configured to receive the third fasteners 204, asshown in FIG. 32 . A third fastener 204 is threaded into one of thesecond threaded openings 202 and turned until it sits flush with therear surface 238 of the retention plate 206, as shown in FIG. 32 .

Continuing with FIGS. 30-32 , a plurality of dowel openings 240 areformed in the retention plate 206 for receiving third alignment dowels242, as shown in FIG. 39 . The third alignment dowels 242 assist inproperly aligning the retention plate 206 and the stuffing box 198 onthe housing 60 during assembly.

Turning back to FIG. 29 , since fluid does not contact the retentionplate 206 during operation, the retention plate 206 may be made of adifferent and less costly material than that of the housing 60 or thestuffing box 198. For example, the retention plate 206 may be made ofalloy steel, while the housing 60 and stuffing box 198 are made ofstainless steel.

Stuffing Box

Turning to FIGS. 29, 33, 34, and 39 , the stuffing box 198 comprisesopposed front and rear surfaces 244 and 246 joined by an outerintermediate surface 248 and a central passage 250 formed therein. Thestuffing box 198 further comprises a front portion 252 joined to a rearportion 254. The front portion 252 has a smaller outer diameter than therear portion 254 such that a medial surface 256 is formed between thefront and rear surfaces 244 and 246. The front portion 252 includes thefront surface 244 of stuffing box 198, and the rear portion 254 includesthe rear surface 246 of the stuffing box 198. An internal shoulder 272is formed within the walls surrounding the central passage 250 withinthe rear portion 254 of the stuffing box 198.

Continuing with FIGS. 33, 34, and 39 , a plurality of passages 258 areformed within the rear portion 254 of the stuffing box 198 andinterconnect the medial surface 256 and the rear surface 246. Thepassages 258 are configured to align with the plurality of firstpassages 234 formed in the retention plate 206 and the plurality offirst threaded openings 194 formed in the rear surface 66 of the housing60, as shown in FIG. 29 .

Continuing with FIGS. 33, 34, and 39 , a plurality of dowel openings 260may be formed in the medial surface 256 of the stuffing box 198. Thedowel openings 260 are configured to receive at least a portion of thethird alignment dowels 242 to properly align the stuffing box 198 on theretention plate 206 and the housing 60 during assembly, as shown in FIG.39 . Likewise, a plurality of dowel openings 268 may be formed in therear surface 246 of the stuffing box 198 for receiving fourth alignmentdowels 270, as shown in FIG. 39 . The fourth alignment dowels 270 assistin properly aligning the rear retainer 200 on the stuffing box 198during assembly.

Continuing with FIG. 39 , the stuffing box 198 is installed within thethird section 76 of the housing 60 such that the front portion 252 isdisposed within the horizontal bore 70 and the medial surface 256 abutsthe rear surface 238 of the retention plate 206. The outer intermediatesurface 248 of the front portion 252 of the stuffing box 198 engages theseal 224. The seal 224 prevents fluid from leaking between the housing60 and the stuffing box 198.

Continuing with FIG. 39 , during operation, the seal 224 wears againstthe outer intermediate surface 248 of the front portion 252. Should thefront portion 252 begin to erode, the stuffing box 198 may be removedand replaced with a new stuffing box 198. Likewise, the seal 224 wearsagainst the wear ring 222 during operation. The wear ring 222 ispreferably made of a harder and more wear resistant material than thehousing 60, such as tungsten carbide. Should the wear ring 222 begin toerode, the wear ring 222 can be removed and replaced with a new wearring 222. Trapping the seal 224 between replaceable parts protects thehousing 60 over time.

Rear Retainer

Turning to FIGS. 29, 35, 36, and 39 , the rear retainer 200 comprisesopposed front and rear surfaces 276 and 278 joined by an outerintermediate surface 280 and a central passage 282 formed therein. Aplurality of passages 284 are formed in the rear retainer 200 andsurround the central passage 282. The passages 284 interconnect thefront and rear surfaces 276 and 278 of the rear retainer 200 and areconfigured to align with the passages 258 formed in the rear portion 254of the stuffing box 198, as shown in FIG. 29 . A plurality of dowelopenings 286 are formed in the front surface 276 of the rear retainer200 for receiving a portion of the fourth alignment dowels 270, as shownin FIG. 39 .

Continuing with FIGS. 35, 36, 39, and 40 , an internal shoulder 279 isformed within the walls surrounding the central passage 282 of the rearretainer 200. Internal threads 288 are formed in the walls surroundingthe central passage 282 and positioned between the internal shoulder 279and the rear surface 278. The internal threads 288 are configured toreceive a packing nut 290, as shown in FIG. 39 . The walls positionedbetween the internal shoulder 279 and the front surface 276 are flat andinclude one or more lube ports 292. The lube port 292 interconnects thecentral passage 282 and the outer intermediate surface 280 of the rearretainer 200, as shown in FIG. 40 .

Plunger Packing and Packing Nut

Continuing with FIG. 39 , fluid is prevented from leaking around theplunger 216 during operation by a plunger packing 300. The plungerpacking 300 is installed within the stuffing box 198 and comprises aplurality of packing seals 302 sandwiched between first and second metalrings 304 and 306. The first metal ring 304 abuts the internal shoulder272 formed within the stuffing box 198 and the second metal ring 306extends into the central passage 282 formed in the rear retainer 200.The second metal ring 306 is known in the art as a “lantern ring”. Oneor more passages 303, shown in FIG. 29 , may be formed in the secondmetal ring 306 and fluidly connect with the one or more lube ports 292formed in the rear retainer 200. During operation, oil used to lubricatethe plunger 216 and plunger packing 300 is supplied through the lubeport 292 and second metal ring 306.

With reference to FIGS. 37-39 , the plunger packing 300 is retainedwithin the stuffing box 198 and the rear retainer 200 using the packingnut 290. The packing nut 290 comprises opposed front and rear surfaces308 and 310 joined by an outer intermediate surface 312 and a centralpassage 314 formed therein. External threads 316 are formed in a portionof the outer intermediate surface 312 for engaging the internal threads288 formed in the rear retainer 200, as shown in FIG. 39 . When thepacking nut 290 is installed within the rear retainer 200, the frontsurface 308 of the packing nut 290 engages and compresses the plungerpacking 300, as shown in FIG. 39 . When compressed, the packing seals302 of the plunger packing 300 tightly seal against an outer surface ofthe plunger 216.

Continuing with FIG. 39 , during operation, the packing nut 290 may betightened, as needed, to ensure adequate compression of the packingseals 302 against the plunger 216. At least a portion of the packing nut290 projects from the rear surface 278 of the rear retainer 200 toprovide clearance to turn the packing nut 290, as needed. The centralpassage 314 formed in the packing nut 290 is sized to closely receivethe plunger 216. A groove 318 may be formed in the walls surrounding thecentral passage 314 for receiving a seal 320. The seal 320 shown in FIG.39 is an O-ring. The seal 320 prevents fluid from leaking around theplunger 216 during operation.

Assembly of Components on Rear Surface of Housing

Turning back to FIG. 29 , the front surface 276 of the rear retainer 200abuts the rear surface 246 of the stuffing box 198 such that theplurality of passages 284 align with the plurality of passages 258formed in the stuffing box 198. A second fastener 196 is installedwithin a corresponding one of the aligned first threaded openings 194and passages 234, 258, and 284. A first end 294 of the second fastener196 threads into the first threaded opening 194 and a second end 296projects from the rear surface 278 of the rear retainer 200. A nut 298is threaded onto the second end 296 and torqued against the rear surface278, tightly securing the stuffing box 198 and the rear retainer 200 tothe third section 76 of the housing 60.

Continuing with FIG. 29 , the nut 298 shown in the figures is 12-pointflange nut. In alternative embodiments, the nut may comprise thethree-piece fastener 90, shown in FIGS. 19-21 . The second fastener 196shown in the figures is a threaded stud. In alternative embodiments, thesecond fastener 196 may comprise other fasteners known in the art, suchas a bolt or screw.

Continuing with FIG. 29 , the stuffing box 198 and rear retainer 200 areattached to the housing 60 after the retention plate 206 has first beenattached to the rear surface 66 of the housing 60. The plunger packing300 may be installed within stuffing box 198 either before or after thestuffing box 198 is attached to the housing 60. After all the componentsare assembled, the packing nut 290 is threaded into the rear retainer200 until it engages the plunger packing 300.

With reference to FIGS. 29 and 39 , when the retention plate 206, thestuffing box 198, and rear retainer 200 are attached to the housing 60,the central opening 239 of the retention plate 206 and the centralpassages 250 and 282 of the stuffing box 198 and the rear retainer 200form an extension of the horizontal bore 70. Likewise, the interior ofthe plunger packing 300 and the central passage 314 of the packing nut290 also form extensions of the horizontal bore 70. The plunger 216 isinstalled within the fluid end section 56 through the rear surface 310of the packing nut 290. During operation, the plunger 216 reciprocateswithin the horizontal bore 70, creating the variance in fluid pressurewithin the fluid end section 56 during operation.

With reference to FIGS. 3, 39, and 40 , as will be discussed in moredetail later herein, during operation, reciprocal movement of theplunger 216 is driven by a pony rod 322 installed within the power endassembly 54. A clamp 324 secures the plunger 216 to the pony rod 322such that the plunger 216 and pony rod 322 move in unison.

Components Installed within the Housing

Turning to FIGS. 40-79 , the various internal components of the housing60 will now be described in more detail. Fluid is routed throughout thehousing 60 by the fluid routing plug 132. The timing of movementthroughout the fluid routing plug 132 is controlled by the suction valve214 and the discharge valve 138. Movement of the valves 214 and 138 isguided by the suction valve guide 212 and the discharge plug 120.

Fluid Routing Plug

Turning to FIGS. 40-59 , the fluid routing plug 132 comprises a body 330having a suction surface 332 and an opposed discharge surface 334 joinedby an outer intermediate surface 336. A central longitudinal axis 338extends through the body 330 and the suction and discharge surfaces 332and 334. When the fluid routing plug 132 is installed within the housing60, at least a portion of the discharge surface 334 is positioned withinthe first section 72 of the housing 60, and at least a portion of thesuction surface 332 is positioned within the third section 76 of thehousing 60, as shown in FIGS. 40 and 41 .

Continuing with FIGS. 43-59 , the body 330 further comprises a pluralityof suction fluid passages 340. The suction passages 340 interconnect theintermediate surface 336 and the suction surface 332 of the body 330, asshown in FIG. 48 . The connection is formed within a blind bore 342formed within the suction surface 332 of the body 330. The blind bore342 may be referred to as an axially-blind bore 342 because it is blindalong the longitudinal axis 338 of the body 330. During operation, fluidentering the housing 60 through the suction bores 160 and 162 flows intothe suction passages 340 of the fluid routing plug 132 and into theaxially-blind bore 342. From there, fluid flows towards the suctionsurface 332 of the body 330 and out of the fluid routing plug 132. Threesuction fluid passages 340 are shown in FIGS. 43-59 . In alternativeembodiments, more or less than three suction fluid passages 340 may beformed within the body 330.

Continuing with FIGS. 49 and 50 , each suction passage 340 has agenerally oval or tear drop cross-sectional shape. An opening 344 ofeach suction passage 340 on the intermediate surface 336 comprises afirst side wall 346 joined to a second side wall 348 by first and secondends 350 and 352. The first and second side walls 346 and 348 arestraight lines of equal length S, and the first and second ends 350 and352 are circular arcs, as shown in FIG. 50 .

Continuing with FIG. 50 , the first end 350 of the opening 344 has aradius of R1 with a center at C1, and the second end 352 has a radius ofR2 with a center at C2. The first end 350 is larger than the second end352 such that R1>R2. The first and second side walls 346 and 348 aretangent to the first and second ends 350 and 352 and have an includedangle, σ.

Continuing with FIG. 50 , the opening 344 has a centerline 354 thatconnects the centers C1 and C2 of the first and second ends 350 and 352.The centerline 354 has a length E and is parallel with the centrallongitudinal axis 338. A cross-sectional shape of each suction passage340 throughout the length of the body 330 corresponds with the shape ofeach opening 344, as shown in FIG. 55 . Each suction passage 340 issized and shaped to maximize fluid flow through the passage 340 andminimize fluid turbulence and stress to the body 330 of the fluidrouting plug 132.

With reference to FIGS. 55 and 56 , each suction fluid passage 340extends between the axially-blind bore 342 and the suction surface 332such that each suction passage 340 comprises a longitudinal axis 356.The longitudinal axis 356 extends through the center C1 of the first end350 of the opening 344 and intersects the central longitudinal axis 338,as shown in FIG. 56 .

Continuing with FIGS. 43-59 , the body 330 further comprises a pluralityof discharge fluid passages 360. The discharge passages 360 interconnectthe suction surface 332 and the discharge surface 334 of the body 330and do not intersect any of the suction passages 340. Rather, thedischarge and suction passages 360 and 340 are in a spaced-relationship.In operation, fluid exiting the body 330 at the suction surface 332 issubsequently forced into the discharge passages 360, towards thedischarge surface 334 of the body 330, and out of the fluid routing plug132. Three discharge fluid passages 360 are shown in FIGS. 43-59 . Inalternative embodiments, more or less than three discharge fluidpassages 360 may be formed within the body 330.

Continuing with FIGS. 43, 46, and 48 , the suction surface 332 of thebody 330 comprises an outer rim 362 joined to the axially-blind bore 342by a tapered seating surface 366, as shown in FIGS. 46 and 48 .Likewise, the discharge surface 334 comprises an outer rim 368 joined toa central base 370 by a tapered seating surface 372, as shown in FIGS.43 and 48 .

Continuing with FIGS. 43, 46, and 48 , each discharge passage 360 opensat a first opening 374 on the outer rim 362 of the suction surface 332and opens at a second opening 376 on the central base 370 of thedischarge surface 334. The second openings 376 surround a blind bore 378formed in the central base 370 of the discharge surface 334. The blindbore 378 is configured to engage a tool used to grip the fluid routingplug 132, as needed. For example, the walls of the blind bore 378 may bethreaded. The central base 370 may also be slightly recessed from thetapered seating surface 372 such that a small counterbore 380 iscreated. The counterbore 380 helps further reduce any turbulence offluid exiting the second openings 376.

Continuing with FIG. 54 , a position of the first and second openings374 and 376 of each discharge passage 360 may be determined relative toa plane containing a line 382 that is perpendicular to the centrallongitudinal axis 338. The first opening 374, when projected onto theplane, is positioned at a first distance F1 from the centrallongitudinal axis 338 and at a first angle φ1 relative to the line 382.The second opening 376, when projected onto the plane, is positioned ata second distance F2 from the central longitudinal axis 338 and at asecond angle φ2 relative to the line 382.

The first and second distances F1 and F2 shown in FIG. 54 are different.Likewise, the first and second angles φ1 and φ2 shown in FIG. 54 aredifferent. In alternative embodiments, the first and second angles φ1and φ2 may be different, but the first and second distances F1 and F2may be the same. In further alternative embodiments, the first andsecond angles φ1 and φ2 may be the same, but the first and seconddistances F1 and F2 may be different. In even further alternativeembodiments, the first and second distances F1 and F2 may be the same,and the first and second angles φ1 and φ2 may be the same.

With reference to FIGS. 51-53 and 56-59 , each discharge passage 360 hasan arced cross-sectional shape. The length of the are may graduallyincrease between the suction and discharge surfaces 332 and 334, asshown in FIGS. 51-53 . In alternative embodiments, the dischargepassages 360 may have different shapes and sizes.

Turning back to FIGS. 44 and 48 , a first annular groove 384 is formedin the outer intermediate surface 336 of the body 330 for housing thefirst seal 386. The first groove 384 is positioned adjacent thedischarge surface 334 and is characterized by two sides walls 388 joinedby a base 390. When the fluid routing plug 132 is installed within thehousing 60, the first seal 386 engages an outer surface of the wear ring136 installed within the first section 72 of the housing 60, as shown inFIGS. 40 and 41 . During operation, the first seal 386 wears against thewear ring 136. If the wear ring 136 begins to erode, the wear ring 136may be removed and replaced with a new wear ring 136. The wear ring 136has an annular shape and may be made of a harder and more wear resistantmaterial than the housing 60. For example, the housing 60 may be made ofstainless steel and the wear ring 136 is made of tungsten carbide.

With reference to FIGS. 42, 44, and 48 , a second annular groove 392 isformed in the outer intermediate surface 336 of the body 330 for housinga second seal 394. The second groove 392 is positioned adjacent thesuction surface 332 and is characterized by a plurality of side walls396 joined by a base 398, as shown in FIG. 42 . Four side walls 396 areshown in FIG. 42 such that the groove 392 has a rounded shape. When thefluid routing plug 132 is installed within the housing 60, the secondseal 394 engages an outer surface of the hardened insert 210, as shownin FIG. 42 . During operation, the second seal 394 wears against theinsert 210. If the insert 210 begins to erode, the insert 210 may beremoved and replaced with a new insert 210.

Continuing with FIGS. 42, 44, and 48 , the outer intermediate surface336 of the body 330 further comprises an annular shoulder 400 formed inthe body 330. The shoulder 400 is positioned between the opening 344 ofthe suction passages 340 and the second groove 392. When the fluidrouting plug 132 is installed within the housing 60, the shoulder 400abuts a front surface 416 of the insert 210, as shown in FIG. 42 . Axialmovement of the fluid routing plug 132 towards the rear surface 66 ofthe housing 60 is prevented by the engagement between the shoulder 400and the insert 210. During operation, the shoulder 400 may wear againstthe insert 210. If either feature begins to wear, the fluid routing plug132 and/or the insert 210 may be removed and replaced with a new fluidrouting plug 132 and/or insert 210.

Continuing with FIGS. 40, 41, 44, and 48 , the outer intermediatesurface 336 of the body 330 adjacent the first groove 384 ischaracterized as a first cylindrical surface 404. Likewise, the outerintermediate surface 336 adjacent the annular shoulder 400 ischaracterized as a second cylindrical surface 406. The first cylindricalsurface 404 has a maximum outer diameter that is equal or almost equalto a maximum outer diameter of the second cylindrical surface 406. Thesurfaces 404 and 406 are configured to closely face the wallssurrounding the horizontal bore 70 within the second section 74 of thehousing 60, as shown in FIGS. 40 and 41 .

Continuing with FIGS. 40, 41, 44, 48, and 49 , the outer intermediatesurface 336 of the body 330 further comprises a first bevel 408 joinedto a transition surface 410 formed in the body 330. The first bevel 408and the transition surface 410 are positioned between the firstcylindrical surface 404 and the openings 344 of the suction passages340. The outer intermediate surface 336 of the body 330 slowly tapersoutward from the transition surface 410 to the second cylindricalsurface 406.

Continuing with FIGS. 40 and 41 , when the fluid routing plug 132 isinstalled within the housing 60, the first bevel 408 provides clearancebetween the outer intermediate surface 336 of the fluid routing plug 132and an opening of the suction bores 160 and 162. Such clearance givesway to an annular fluid channel 412 formed between the housing 60 andthe fluid routing plug 132. The shape of the outer intermediate surface336 of the fluid routing plug 132 between the first and secondcylindrical surfaces 404 and 406 helps direct fluid flowing from thesuction bores 160 and 162 into the openings 344 of the suction passages340 while minimizing fluid turbulence.

Turning back to FIG. 42 , the outer intermediate surface 336 of the body330 further comprises a second bevel 414 formed in the body 330. Thesecond bevel 414 is positioned between the suction surface 332 and thesecond groove 392. The second bevel 414 provides clearance to helpinstall the fluid routing plug 132 within the housing 60 and the insert210.

Hardened Insert

With reference to FIGS. 42 and 60-63 , the insert 210 has an annularshape and comprises opposed front and rear surfaces 416 and 418 joinedby inner and outer intermediate surfaces 420 and 422. The insert 210further comprises a first bevel 426 formed in the inner intermediatesurface 420 adjacent the front surface 416, as shown in FIG. 63 . Thefirst bevel 426 provides clearance to assist in installing the fluidrouting plug 132 within the insert 210 within the housing 60, as shownin FIG. 42 . The insert 210 also comprises a second bevel 424 formed inthe outer intermediate surface 422 adjacent the rear surface 418. Thesecond bevel 424 provides clearance to assist in installing the insert210 within the counterbore 208 formed in the third section 76 of thehousing 60, as shown in FIG. 42 . The insert 210 is made of a harder andmore wear resistant material than the housing 60. For example, if thehousing 60 is made of stainless steel, the insert 210 may be made oftungsten carbide.

Suction and Discharge Valves

With reference to FIGS. 40, 41, and 64-67 , the flow of fluid throughoutthe housing 60 and the fluid routing plug 132 is regulated by thesuction and discharge valves 214 and 138. The suction valve 214 isconfigured to engage the suction surface 332, and the discharge valve138 is configured to engage the discharge surface 334 of the fluidrouting plug 132 such that the surfaces 332 and 334 function as valveseats. The valves 214 and 138 are similar in shape but may vary in size.As shown in FIGS. 40 and 41 , the discharge valve 138 is slightly largethan suction valve 214.

Continuing with FIGS. 64-67 , the discharge valve 138 is shown in moredetail. The suction valve 214 has the same features as the dischargevalve 138 so only the discharge valve 138 is shown in more detail in thefigures. The discharge valve 138 comprises a stem 402 joined to a body428. The body 428 comprises an outer rim 430 joined to a valve insert432 by a tapered seating surface 434. An annular cutout 436 formedwithin the seating surface 434 is configured to house a seal 438, asshown in FIG. 67 .

Continuing with FIGS. 40 and 41 , during operation, the seating surface434 and the seal 438 engage the seating surface 372 of the dischargesurface 334 and block fluid from entering or exiting the dischargepassages 360, as shown in FIG. 40 . Likewise, the seating surface 434and the seal 438 on the suction valve 214 engage the seating surface 366of the suction surface 332 and block fluid from entering or exiting thesuction passages 340, as shown in FIG. 41 .

Continuing with FIGS. 40 and 41 , when the seating surfaces 434 and 372are engaged, the valve insert 432 extends partially into the counterbore380 formed in the discharge surface 334. Fluid exiting the secondopenings 376 of the discharge passages 360 contacts the insert 432,pushing the discharge valve 138 away from the discharge surface 334before flowing around the seating surface 434 of the discharge valve138. Such motion enlarges the area for fluid to flow between the seatingsurfaces 372 and 434 before fluid reaches the surfaces 372 and 434,thereby reducing the velocity of fluid flow within such area. Thelowered fluid velocity between the surfaces 372 and 434 causes any wearto the valve 138 or 214 to be concentrated at the insert 432 instead ofthe crucial sealing elements, thereby extending the life of the valve138 or 214.

Likewise, the insert 432 on the suction valve 214 extends partially intothe opening of the axially-blind bore 342. Fluid within theaxially-blind bore 342 contacts the insert 432 before flowing around theseating surface 434 and seal 438 of the suction valve 214. Such motionenlarges the area for fluid to flow between the seating surfaces 366 and434 before fluid reaches the surfaces 366 and 434, thereby reducing thevelocity of fluid flow within such area.

Continuing with FIGS. 64-67 , the stem 402 projects from a top surface440 of the body 428 of the valve 138 or 214. The outer rim 430 surroundsthe stem 402 and is spaced from the stem 402 by an annular void 442. Agroove 444 is formed in the outer rim 430 for receiving a portion of aspring 446, as shown in FIGS. 40 and 41 .

Continuing with FIGS. 40 and 41 , during operation, the valves 138 and214 move axially along the longitudinal axis 62 of the housing 60between open and closed positions. In the closed position, the seatingsurface 434 and the seal 438 of each of the valves 138 and 214 tightlyengage the corresponding seating surface 372 or 366 of the fluid routingplug 132 and the valve insert 432 is disposed within the correspondingbore 380 or 342. In the open position, the seating surface 434 and theseal 438 are spaced from the corresponding seating surface 372 or 366 ofthe fluid routing plug 132 and the valve insert 432 is spaced from thecorresponding bore 380 or 342.

Suction Valve Guide

With reference to FIGS. 40, 41, and 68-71 , axial movement of thesuction valve 214 is guided by the suction valve guide 212. The suctionvalve guide 212 comprises a thin-walled skirt 448 joined to a body 450by a plurality of support arms 452. The skirt 448 comprises a taperedupper section 454 joined to a cylindrical lower section 456. Theplurality of arms 452 join the tapered upper section 454 to the body450. A plurality of flow ports 458 are formed between adjacent arms 452such that fluid may pass through the suction valve guide 212 duringoperation.

Continuing with FIGS. 40 and 41 , the suction valve guide 212 isinstalled within the housing 60 such that the tapered upper section 454engages a tapered surface 455 of the walls surrounding the horizontalbore 70. Such engagement prevents further axial movement of the suctionvalve guide 212 within the housing 60. When the suction valve guide 212is installed within the housing 60, the skirt 448 covers the walls ofthe housing 60 positioned between the flow ports 458 and the fluidrouting plug 132. During operation, fluid wears against the skirt 448,thereby protecting the housing 60 from wear and erosion. If the skirt448 begins to erode, the suction valve guide 212 can be removed andreplaced with a new guide 212.

Continuing with FIGS. 40, 41, and 68-71 , the body 450 of the suctionvalve guide 212 is tubular and is centered within the skirt 448. Atubular insert 460 is installed within the body 450, as shown in FIG. 71. The insert 460 is configured to receive the stem 402 of the suctionvalve 214, as shown in FIGS. 40 and 41 . During operation, the stem 402moves axially within the insert 460 and wears against the insert 460. Anannular cutout 462 formed in the stem 402, shown in FIGS. 66 and 67 ,provides space for any fluid or other material trapped between the stem402 and the insert 460. The insert 460 is made of a harder and more wearresistant material than the body 450 thereby extending the life of thesuction valve guide 212. For example, if the body 450 is made ofstainless steel, the insert 460 may be made of tungsten carbide.

Continuing with FIGS. 40 and 41 , a spring 446 is positioned between theouter rim 430 of the suction valve 214 and the plurality of arms 452such that the spring 446 surrounds at least a portion of the body 450 ofthe suction valve guide 212. During operation, the spring 446 biases thesuction valve 212 in a closed position, as shown in FIG. 41 . Fluidpushing against the valve insert 432 moves the suction valve 214 axiallyto compress the spring 446 and move the suction valve 214 to an openposition, as shown in FIG. 40 .

Discharge Plug

With reference to FIGS. 40, 41, and 72-75 , axial movement of thedischarge valve 138 is guided by the discharge plug 120. The dischargeplug 120 comprises a pair of legs 464 joined to a body 466. The body 466comprises a front portion 468 joined to a rear portion 470 by a medialportion 472. The medial portion 472 has a larger outer diameter thanboth the front and rear portions 468 and 470. An outer surface of themedial portion 472 engages the seal 126 installed within the firstsection 72 of the housing 60, as shown in FIGS. 40 and 41 . The pair oflegs 464 are joined to the medial portion 472 and extend between themedial portion 472 and the discharge surface 334 of the fluid routingplug 132.

Continuing with FIGS. 40, 41, and 72-75 , a dowel opening 474 is formedin the outer surface of the medial portion 472 for receiving thelocating dowel pin 130. The discharge plug 120 is installed within thefirst section 72 of the housing 60 such that the locating dowel pin 130is installed within the dowel opening 474 formed in the medial portion472 and the locating cutout 128 formed in the first section 72 of thehousing 60. Such installation aligns the discharge plug 120 within thehousing 60 so that the pair of legs 464 do not block the openings of theupper and lower discharge bores 102 and 104.

Continuing with FIGS. 40 and 41 , the locating cutout 128 may be largeenough to provide sufficient clearance for installation of the locatingdowel pin 130 within the locating cutout 128. The locating cutout 128 issized to allow maximum clearance for assembly, but still maintain anacceptable rotational position of the discharge plug 120. For example,the cutout 128 may be a maximum of 15 degrees wide along thecircumference of the horizontal bore 70.

Continuing with FIG. 75 , an axially-blind bore 476 extends within thebody 466 and opens on the rear portion 470 of the body 466. The bore 476is sized to receive a tubular insert 478. The tubular insert 478 issimilar to the tubular insert 460 installed within the suction valveguide 212. The tubular insert 478 is configured to receive the stem 402of the discharge valve 138, as shown in FIGS. 40 and 41 .

Continuing with FIGS. 40, 41, and 75 , during operation, the stem 402moves axially within the tubular insert 478. A plurality of passages 480are formed in the body 466 and interconnect the bore 476 and an outersurface of the medial portion 472. During operation, any fluid or othermaterial trapped within the bore 476 exits the discharge plug 120through the passages 480. A spring 446 is positioned between the medialportion 472 of the plug 120 and the outer rim 430 of the discharge valve138, as shown in FIGS. 40 and 41 . The spring 446 biases the dischargevalve 138 in the closed position, as shown in FIG. 40 . Fluid pushingagainst the valve insert 432 moves the discharge valve 138 axially tocompress the spring 446 and move the discharge valve 138 to an openposition, as shown in FIG. 41 .

Continuing with FIGS. 40, 41, 72, and 75 , the front portion 468 of thebody 466 is sized to be disposed within a counterbore 482 formed withinthe front retainer 118. When disposed therein, a rear surface 484 of thefront retainer 118 abuts an outer surface of the medial portion 472 ofthe discharge plug 120, as shown in FIGS. 40 and 42 . Such engagementholds the discharge plug 120 in place between the front retainer 118 andthe fluid routing plug 132. A blind bore 486 is formed in an outersurface of the front portion 468 of the plug 120. The blind bore 486 isconfigured to engage a tool used to help install or remove the plug 120from the housing 60. For example, the bore 486 may have threaded walls.

Front Retainer

With reference to FIGS. 40, 41, 76, and 77 , the front retainer 118comprises opposed front and rear surfaces 488 and 484 joined by an outersurface having external threads 124 and a horizontal bore 490 formedtherein. The horizontal bore 490 comprises a hex portion 492 that opensin the counterbore 482, as shown in FIGS. 40 and 41. The hex portion 492is configured to mate with a tool used to thread the front retainer 118into the housing 60 until it abuts the discharge plug 120, as shown inFIGS. 40 and 41 . An annular void 494 is formed within the front surface488 of the front retainer 118. The annular void 494 decreases the weightof the front retainer 118, making it easier to thread into the housing60.

Discharge Conduits and Manifold

With reference to FIG. 41 , each discharge fitting 108 comprises asupport base 502 and a connection end 512. A discharge fitting adapter504 is installed within the counterbore 106 formed in the upper andlower discharge bores 102 and 104. When installed, the seal 112 engagesan outer surface of the fitting adapter 504. A groove 505 is formed withthe discharge fitting 108 for receiving a second seal 507. The secondseal 507 likewise engages an outer surface of the fitting adapter 504.

Continuing with FIG. 41 , the support base 502 is sized to abut theouter intermediate surface 68 of the first section 72 of the housing 60.The support base 502 comprises a plurality of passages 506, shown inFIG. 29 , configured to align with the threaded openings 114 formed inthe intermediate surface 68 and surrounding the discharges bores 102 and104. The threaded fasteners 116 are installed within the alignedpassages 506 and openings 114 and tightened to secure the dischargefitting 108 to the first section 72.

With reference to FIGS. 3 and 41 , the connection end 512 of thedischarge fitting 108 is configured to mate within one or more dischargeconduits 500 included in an upper or lower discharge manifold 514 or516, as shown in FIG. 3 . The upper and lower discharge manifolds 514and 516 are supported on rack 518, as shown in FIG. 3 . The fluid endassembly 52 is disposed within the interior open area of the rack 518.The rack 518 supports the upper and lower discharge manifolds 514 and516 in a spaced position from the discharge bores 102 and 104. As aresult, each discharge conduit 500 has an angled or bent shape. Inoperation, fluid discharges from the housing 60 through upper and lowerdischarge bores 102 and 104 and is carried to the corresponding upper orlower discharge manifolds 514 or 516 by the discharge fittings andconduits 108 and 500.

Suction Conduits and Manifold

With reference to FIGS. 41 and 78 , each suction conduit 166 comprisesthe first connection member 164 joined to a second connection member 520by threads, as shown in FIG. 78 . The first and second connectionmembers 164 and 520 may be made of a metal or hardened material.

Continuing with FIG. 78 , the first connection member 164 comprisesupper portion 524 joined to a lower portion 526. External threads 172are formed on a portion of the lower portion 526 for mating with theinternal threads 170 formed in the suction bores 160 or 162. The seal176 installed within the housing 60 engages a cylindrical outer surfaceof the lower portion 526 below the external threads 172. The upperportion 524 has a larger outer diameter than the lower portion 526 andis positioned outside of the housing 60. The lower portion 526 abuts thecounterbore 168 of the suction bores 160 and 162 of the second section74 of the housing 60.

With reference to FIGS. 3 and 78 , the second connection member 520 isconfigured to mate with one or more connection members or hoses 528formed on an upper or lower suction manifold 530 or 532. The upper andlower suction manifolds 530 and 532 are supported on the rack 518adjacent the discharge manifolds 514 and 516. The connection members orhoses 528 may be flexible so that they may bend, as needed, to properlyinterconnect the suction conduits 166 and the suction manifolds 530 and532. In operation, fluid is drawn into the housing 60 from the suctionmanifolds 530 and 532 via the connection members 528, the suctionconduits 166, and the upper and lower suction bores 160 and 162.

Assembly of Fluid End Section and Assembly

Turning to FIGS. 9, 29, 79, and 80 , prior to assembling the housing 60,the wear ring 136 is preferably first pressed into the counterbore 134formed in the first section 72 of the housing 60. Likewise, the hardenedinsert 210 is pressed into the counterbore 208 formed in the thirdsection 76 of the housing 60. The seals 126, 112, and 176 may also beinstalled within the first and second sections 72 and 74 of the housing60. The wear ring 222 and seal 224 may also be installed within thethird section 76 of the housing 60 prior to assembling the housing 60.

Following installation of the above described components, the housing 60may be assembled as described above. Thereafter, the retention plates206, stuffing box 198, rear retainer 200, plunger packing 300, andpacking nut 290 may be attached to the rear surface 66 of the housing60. The inner components of the housing 60 are inserted within thehousing 60 through the front surface 64 of the first section 72. Theinner component may be installed prior to attaching the components tothe rear surface 66 of the housing 60, if desired. Following assembly ofeach fluid end section 56, each section 56 is attached to the power endassembly 54 using the stay rods 58.

Each fluid end section 56 and its various components are heavy andcumbersome. Various tools or lifting mechanisms may be used to assemblethe fluid end assembly 52 and attach it to the power end assembly 54,creating the high pressure pump 50.

Operation of Fluid End Assembly

Turning back to FIGS. 40 and 41 , in operation, retraction of theplunger 216 out of the housing 60 pulls fluid from the upper and lowersuction bores 160 and 162 into the suction passages 340 within the fluidrouting plug 132. Fluid flowing through the suction passages 340 andinto the axially-blind bore 342 pushes on the valve insert 432 of thesuction valve 214, causing the valve 214 to compress the spring 446 andmove to an open position, as shown in FIG. 40 . When in the openposition, fluid flows around the suction valve 214 and the suction valveguide 212 and into the open horizontal bore 70 within the third section76 of the housing 60.

Continuing with FIG. 41 , extension of the plunger 216 further into thehousing 60 pushes against fluid within the open horizontal bore 70 andforces the fluid towards the suction surface 332 of the fluid routingplug 132. Such motion also causes the suction valve 214 to move to aclosed position, sealing the opening of the axially-blind bore 342.Because the bore 342 is sealed, fluid is forced into the dischargepassages 360.

Fluid flowing through the discharge passages 360 contacts the valveinsert 432 on the discharge valve 138, causing the discharge valve 138to compress the spring 446 and move into an open position, as shown inFIG. 41 . When in the open position, fluid flows around the dischargevalve 138 and into the upper and lower discharge bores 102 and 104.Because fluid exiting the discharge passages 360 has been compressed byextension of the plunger 216 into the housing 60, such fluid has ahigher fluid pressure than that entering the housing 60 through thesuction bores 160 and 162.

During operation, the plunger 216 continually reciprocates within thehousing 60, pressuring all fluid drawn into the housing 60 through thesuction bores 160 and 162. Pressurized fluid exiting the housing 60through the upper and lower discharge bores 102 and 104 is delivered tothe upper and lower discharge manifolds 514 and 516 in communicationwith each of the fluid end sections 56. Pressurized fluid within thedischarge manifolds 514 and 516 is eventually delivered to the wellhead18, as shown in FIG. 2 .

Power End Assembly

Turning now to FIGS. 81-141 , the power end assembly 54 is shown in moredetail. The power end assembly 54 comprises a crank section 600 joinedto a crosshead section 602 by a plurality of stay rods 604, as shown inFIG. 84 . The stay rods 604 may be characterized as a plurality of firststay rods or a first set of stay rods 604, while the stay rods 58, shownin FIGS. 4, 5, and 83 , may be characterized as a plurality of secondstay rods or a second set of stay rods 58. As will be described in moredetail herein, the first set of stay rods 604 secure the components ofthe power end assembly 54 together, while the second set of stay rods 58secure the fluid end assembly 52 to the power end assembly 54.

Continuing with FIGS. 82-84 , as will be described in more detailherein, the crank section 600 is configured to house a crankshaft 606,and the crosshead section 602 is configured to house a plurality ofcrossheads 608. Each crosshead 608 is supported within a crosshead guide610 and is attached to the crankshaft 606 by a connecting rod 612.Rotation of the crankshaft 606 causes the connecting rod 612 toreciprocate the crosshead 608 within the crosshead guide 610. A pony rod322 interconnects each plunger 216 within a corresponding one of thecrossheads 608. As the crosshead 608 reciprocates within the crossheadguide 610, the crosshead 608 causes the pony rod 322 and connectedplunger 216 to reciprocate, thereby reciprocating the plunger 216 withineach fluid end section 56. The various components of the power endassembly 54 will now be described in more detail.

Crank Section

Crank Frame

With reference to FIGS. 85-93 , the crank section 600 comprises a crankframe 616 made of a single casting or of single-piece construction. Thecrank frame 616 comprises opposed front and rear surfaces 618 and 620joined by inner and outer intermediate surfaces 622 and 624, as shown inFIGS. 87 and 89 . The inner intermediate surface 622 defines a pluralityof support members 626 sized to receive and support the crankshaft 606,as shown in FIG. 95 . The outer intermediate surface 624 comprisesopposed first and second sides 628 and 630 and upper and lower surfaces632 and 634.

Continuing with FIGS. 87, 89, and 90 , the crank frame 616 comprisesfour support members 626 equally spaced between the first and secondsides 628 and 630 of the frame 616. Together, the support members 626and sides 628 and 630 define five rectangular shaped cavities 636 formedwithin the crank frame 616. As will be discussed in more detail herein,each cavity 636 is sized to receive a corresponding one of theconnecting rods 612, as shown in FIG. 82 .

Continuing with FIGS. 87-90, and 93 , a plurality of passages 638 areformed in the crank frame 616 adjacent its upper and lower surfaces 632and 634. Each passage 638 interconnects the front and rear surfaces 618and 620 of the frame 616 and is sized to receive one of the first stayrods 604 in a one-to-one relationship, as shown in FIG. 112 . Thepassages 638 are positioned such that four passages 638 surround asingle cavity 636, two passages 638 are adjacent the upper corners ofthe cavity 636 and two passages 638 are adjacent the lower corners ofthe cavity 636, as shown in FIGS. 87 and 89 .

Continuing with FIGS. 87, 88, and 92 , the front surface 618 of thecrank frame 616 further comprises a plurality of bosses 640. The bosses640 are features formed on the sides of each support member 626 andconfigured so that a flat circular surface lies flush with the frontsurface 618 of the frame 616. Four bosses 640 surround each cavity 636.As will be described in more detail herein, the bosses 640 areconfigured to engage an end of each second stay rod 58.

Continuing with FIG. 88 , each boss 640 is surrounded on the frontsurface 618 by a groove 642. The groove 642 is configured to house anO-ring seal 644. The seals 644 prevent lubricant contained within thepower end assembly 54 from leaking between the various components of theassembly 54. A rectangular shaped groove 646 is also formed in the frontsurface 618 around each cavity 636. The groove 646 is configured tohouse a seal 648. The seal 648 likewise prevents lube from leakingbetween the components of the assembly 54.

Continuing with FIGS. 85, 87 and 91 , the upper surface 632 of the crankframe 616 comprises one or more lube ports 650. The lube ports 650connect with a lubrication system 652 supported on the upper surface632, as shown in FIG. 85 . Lube is supplied to the crankshaft 606 duringoperation through the lube ports 650. A lube reservoir 654 is formed ina base 656 of each cavity 636 for collecting lubricant during operation,as shown in FIG. 87 . An opening 658 is formed in the center of eachlube reservoir 654. As will be described in more detail herein, eachopening 658 drains into the lubrication system 652.

Continuing with FIGS. 91-93 , the lower surface 634 of the crank frame616 comprises a plurality of integrally formed feet 660 projecting fromthe front and rear surfaces 618 and 620 of the frame 616. The feet 660are configured to support the frame 616 on a base section 662, as shownin FIG. 83 .

Continuing with FIGS. 87, 89, and 91-94 , the first and second sides 628and 630 and the inner support members 626 each comprise a circularshaped bearing opening 666. The bearing openings 666 are sized to eachreceive a roller bearing 668, as shown in FIG. 94 . The roller bearings668 are secured within each opening 666 by a plurality of brackets 667.The brackets 667 are secured to the sides 628 and 630 and the supportmembers 626 using a plurality of fasteners 669. Each roller bearing 668is sized to receive a portion of the crankshaft 606, as shown in FIG. 95.

Crankshaft

Turning to FIGS. 96-99 , the crankshaft 606 comprises a plurality ofbearing journals 670 and a plurality of rod journals 672. The crankshaft606 is bounded by a first end journal 676 and an opposed second endjournal 678. Adjacent bearing journals 670 are joined by one of the rodjournals 672. Adjacent rod journals 672 are offset from one another. Aplurality of interconnecting lube ports 674 are formed within thebearing journals 670 and the rod journals 672. Together the lube ports674 form a continuous lube pathway throughout the crankshaft 606.

Continuing with FIGS. 96 and 97 , each bearing journal 670 comprises aplurality of threaded openings 671. The openings 671 are positionedaround the periphery of each side of each bearing journal 670. Eachopening 671 is configured to receive a threaded fastener 673, as shownin FIG. 95 .

With reference to FIGS. 95 and 100 , the crankshaft 606 is installedwithin the crank frame 616 such that each bearing journal 670 issupported within a corresponding one of the roller bearings 668. Eachbearing journal 670 is held within a corresponding roller bearing 668 bya plurality of washers 675. A plurality of the washers 675 are attachedto each side of each bearing journal 670 using the fasteners 673. Eachwasher 675 extends past the periphery of each bearing journal 670 andengages an edge of the corresponding roller bearing 668. Such engagementon both sides of each bearing journal 670 and roller bearing 668prevents lateral movement of each bearing journal 670 relative to thecorresponding roller bearing 668.

Continuing with FIGS. 85, 86, 95, and 100 , when the crankshaft 606 isinstalled within the crank frame 616, each bearing journal 670 isrotatable within the corresponding roller bearing 668. The first endjournal 676 is supported within the opening 666 formed within first side628 of the frame 616, as shown in FIG. 86 . The first end journal 676 isconfigured to attach to a gearbox section 678 of the power end assembly54, as shown in FIG. 85 . Rotation of the crankshaft 606 is powered byan engine (not shown) attached to the gearbox section 678. The secondend journal 678 is supported within the roller bearing 668 on the secondside 630 of the frame 616, as shown in FIG. 100 . The second end journal678 may be protected by a cover (not shown) attached to the second side630 of the frame 616.

Continuing with FIGS. 82 and 95 , when the crankshaft 606 is installedwithin the crank frame 616, each rod journal 672 spans between adjacentsupport members 626 and is accessible within the corresponding cavity636, as shown in FIG. 95. Each connecting rod 612 attaches to acorresponding one of the rod journals 672 within each cavity 636, asshown in FIG. 82 .

Crosshead Section

Turning back to FIGS. 85 and 86 , the crosshead section 602 has the sameor almost the same height and width as the crank section 600. Thecrosshead section 602 is positioned offset from and in front of thecrank section 600 such that the power end assembly 54 has the generalshape of a rectangular prism. The crosshead section 602 comprises aplurality of the crosshead guides 610 situated in a side-by-siderelationship. Five crosshead guides 610 are shown in FIGS. 85 and 86 .Each crosshead guide 610 corresponds with one of the cavities 636 formedwithin the crank frame 616. By using individual crosshead guides 610, asingle guide 610 may be removed and replaced with a new guide 610, ifneeded, without replacing the entire crosshead section 602 of theassembly 54.

Crosshead Guide

Continuing with FIGS. 101-112 , each crosshead guide 610 is configuredto receive one of the crossheads 608 in a one-to-one relationship, asshown in FIGS. 111 and 112 . Each crosshead guide 610 has the generalshape of a rectangular prism and comprises opposed front and rearsurfaces 682 and 684 joined by an outer intermediate surface 686 and abore 688 formed therein, as shown in FIGS. 101-110 . The bore 688 shownin FIGS. 101-112 is horizontally positioned.

Continuing with FIGS. 101-112 , the outer intermediate surface 686 ofthe crosshead guide 610 comprises upper and lower surfaces 690 and 692and opposed side surfaces 694. A plurality of first passages 696 areformed in the guide 610 adjacent the upper and lower surfaces 690 and692, as shown in FIGS. 101-105 . Each first passage 696 interconnectsthe front and rear surfaces 682 and 684 and is configured to receive oneof the first stay rods 604, as shown in FIG. 112 . Four first passages696 are shown in FIGS. 101-104 , two passages 696 adjacent the uppersurface 690 and two passages 696 adjacent the lower surface 692. Thefirst passages 696 are positioned such that they align with theplurality of passages 638 formed in the crank frame 616, as shown inFIG. 112 .

Continuing with FIGS. 101-104, 106, and 113 , a plurality of secondpassages 698 are also formed in each crosshead guide 610. The secondpassages 698 interconnect the front and rear surfaces 682 and 684 of theguide 610 and are configured to receive a plurality of the second stayrods 58 in a one-to-one relationship, as shown in FIG. 113 . The secondpassages 698 are positioned between the horizontal bore 688 and theplurality of first passages 696 such that the first and second passages696 and 698 are vertically offset from one another. Four second passages698 are shown in FIGS. 101-104 , two passages 698 closer to the uppersurface 690 and two passages 698 closer to the lower surface 692 of thecrosshead guide 610.

Continuing with FIGS. 101, 102, and 107 , the front surface 682 of thecrosshead guide 610 further comprises a plurality of threaded openings700. The threaded openings 700 surround an opening of the horizontalbore 688 and are configured to receive a plurality of fasteners 702 in aone-to-one relationship, as shown in FIG. 86 . The fasteners 702 areconfigured to secure a pony rod seal plate 704 to the front surface 682of the crosshead guide 610, as shown in FIG. 86 .

Continuing with FIGS. 103, 104, 107, and 108 , the crosshead guide 610further comprises a plurality of exhaust vents 706 formed therein. Eachvent 706 interconnects the horizontal bore 688 and the rear surface 684of the guide 610. Three vents 706 are shown in FIGS. 103 and 104 . Twovents 706 are positioned between the horizontal bore 688 and the uppersurface 690, and a third vent 706 is positioned between the horizontalbore 688 and the lower surface 692. In operation, any air pressureaccumulating within the horizontal bore 688 is vented into the openspace within the crank frame 616 through one or more of the vents 706,as shown in FIG. 111 .

With reference to FIGS. 85, 104, 107-109, and 111 , the crosshead guide610 further comprises a lube port 708 configured to receive lube fromthe lubrication system 652, as shown in FIG. 85 . The lube port 708interconnects the upper surface 690 and the horizontal bore 688 of thecrosshead guide 610, as shown in FIGS. 107 and 111 . In operation,lubricant delivered to the crosshead 608 from the lube port 708eventually drains from the crosshead guide 610 and into the crank frame616 via one or more of the vents 706 and/or the horizontal bore 688, asshown in FIG. 111 . Lubricant is prevented from leaking around thecrosshead guide 610 by a plurality of O-ring seals 710 and 712, as shownin FIG. 109 . The seals 710 are installed within grooves 714 formed inthe rear surface 684 of the guide 610 and surrounding the opening of thevents 706. The seal 712 is installed within a groove 716 formed in therear surface 684 of the guide 610 and surrounding the opening of thehorizontal bore 688.

Continuing with FIGS. 101-108 , each crosshead guide 610 is heavy andmade of a single casting or of single-piece construction and may requirea lifting mechanism to maneuver. To reduce the weight of each crossheadguide 610 as much as possible, a plurality of non-symmetrically shapedholes 718 are formed with the crosshead guide 610 and interconnect thefront and rear surfaces 682 and 684, as shown in FIGS. 105, 106, and 108. The holes 718 remove unnecessary raw material from each guide 610,thereby reducing its weight. Likewise, a plurality of cavities 720 areformed in the sides 694 of each crosshead guide 610, as shown in FIGS.102 and 104 . The cavities 720 remove unnecessary material from eachguide 610, thereby reducing its weight.

Along the same lines, the upper and lower surfaces 690 and 692 of thecrosshead guides 610 and the upper surface 632 of the crank frame 616are shaped to conform to the shape of each of the plurality of firststay rods 604, as shown in FIG. 86 . Shaping the surfaces 690 and 692and 632 and 634 to conform to the shape of the stay rods 604 reducesunnecessary weight from the assembly 54.

Crosshead

Turning to FIGS. 111, 112, and 114-117 , the crosshead 608 comprisesopposed front and rear surfaces 722 and 724 joined by upper and lowersurfaces 726 and 728 and opposed side surfaces 730, as shown in FIGS.114-117 . The upper and lower surfaces 726 and 728 are shaped to conformto the cylindrical walls of the horizontal bore 688 of the crossheadguide 610, as shown in FIGS. 111 and 112 . The front surface 722 isconfigured to attach to a pony rod 322 and the rear surface 724 is sizedto closely face a portion of the connecting rod 612, as shown in FIG.111 . The crosshead 608 is sized to be movable relative to the crossheadguide 610 and along a longitudinal axis 732 of the horizontal bore 688,as shown in FIGS. 111 and 112 .

Continuing with FIGS. 111, 112, and 121-123 , a bore 734 is formedwithin the crosshead 608 and interconnects the opposed side surfaces730, as shown in FIGS. 115 and 116 . When the crosshead 608 is installedwithin the guide 610, the bore 734 extends at a right angle relative tothe bore 688 formed in the guide 610, as shown in FIGS. 111 and 112 .The bore 734 is sized to closely receive a cylindrical bearing 736, asshown in FIGS. 121-123 . The bearing 736 is secured within the bore 734by a plurality of brackets 738 and fasteners 739. The bearing 736 issized to closely receive a cylindrical wrist pin 740. The wrist pin 740is rotatable relative to the bearing 736.

Continuing with FIGS. 118-123 , the wrist pin 740 comprises opposed sidesurfaces 742 joined by a cylindrical intermediate surface 744. A pair ofnotches 746 are formed in each of the sides 742. Each notch 746 exposesa flat medial surface 748 formed within the wrist pin 740. A pluralityof passages 750 are formed within the wrist pin 740 and extend along adiameter of the wrist pin 740. Each passage 750 interconnects the medialsurface 748 and the cylindrical outer intermediate surface 744. Thepassages 750 are configured to receive a plurality of fasteners 752 in aone-to-one relationship. When the wrist pin 740 is installed within thebearing 736, the sides 742 project from the sides 730 of the crosshead608 such that the passages 750 are positioned outside of the crosshead608, as shown in FIG. 123 .

Connecting Rod

Continuing with FIGS. 111, 112, and 121-123 , the connecting rod 612comprises a crosshead connection end 754 joined to a crankshaftconnection end 756 by an elongate body 758. The crosshead connection end754 comprises opposed yoke arms 760 projecting from a medial surface762, as shown in FIGS. 121 and 122 . The yoke arms 760 are U-shaped andare sized to mate with the cylindrical outer intermediate surface 744 ofthe wrist pin 740. A plurality of threaded openings 764 are formed in afront surface 766 of each yoke arm 760. The openings 764 are positionedto align with the passages 750 formed within the wrist pin 740. Afastener 752 is installed within each aligned passage 750 and opening764 to secure the connecting rod 612 to the wrist pin 740, as shown inFIG. 112 . When secured together, the medial surface 762 of thecrosshead connection end 754 of the connecting rod 612 faces and is in aspaced-relationship with the rear surface 724 of the crosshead 608, asshown in FIG. 111 .

Continuing with FIGS. 112 and 121 , a dowel opening 768 formed withineach front surface 766 of each yoke arm 760 aligns with dowel openings770 formed in the cylindrical outer intermediate surface 744 of thewrist pin 740. The openings 768 and 770 are configured to receivealignment dowels 772, as shown in FIG. 112 . The alignment dowels 772properly align the threaded openings 764 and passages 750 duringassembly.

Continuing with FIGS. 111 and 112 , when the connecting rod 612 isrigidly attached to the wrist pin 740, the connecting rod 612 and wristpin 740 move together relative to the crosshead 608. The wrist pin 740is rotatable within the bearing 736 while the elongate body 758 of theconnecting rod 612 is pivotable relative to the crosshead 608.

Continuing with FIGS. 111, 112, and 121-123 , while the crossheadconnection end 754 is integral with the body 758 of the connecting rod612, the crankshaft connection end 756 comprises multiple pieces. Thecrankshaft connection end 756 is configured to clamp around acorresponding one of the rod journals 672 of the crankshaft 606. Thecrankshaft connection end 756 comprises front and rear clamp sections774 and 776. The front clamp section 774 is integrally formed with thebody 758 of the connecting rod 612, while the rear clamp section 776 isa separate piece. The crankshaft connection end 756 further comprises asplit ring bearing 778 configured to be positioned intermediate the rodjournal 672 and the clamp sections 774 and 776, as shown in FIG. 111 .

Continuing with FIGS. 111, 112, and 121-123 , the split ring bearing 778is sized to closely surround the rod journal 672. A semi-circular recess780 is formed within each clamp section 774 and 776, as shown in FIGS.121 and 122 . Each recess 780 is sized to closely receive a portion ofthe ring bearing 778. A plurality of threaded openings 782 are formed ina rear surface 784 of the front clamp section 774, as shown in FIG. 122. The openings 782 correspond with a plurality of passages 786 formed inthe rear clamp section 776, as shown in FIG. 122 . Each passage 786opens into a notch 788 formed in an outer surface of the rear clampsection 776.

Continuing with FIGS. 111, 112, and 123 , a plurality of fasteners 790are installed within each pair of aligned openings 782 and passages 786and tightened to tightly clamp the split ring bearing 778 and the clampsections 774 and 776 around the rod journal 672. The split ring bearing778 allows the crankshaft connection end 756 of the connecting rod 612to rotate relative to the rod journal 672 while the body 758 of theconnecting rod 612 pivots relative to the rod journal 672.

Pony Rod

Continuing with FIGS. 121-123 , the pony rod 322 comprises an elongatecylindrical body 792 having a plunger connection end 794 and an opposedcrosshead connection end 796. The crosshead connection end 796 comprisesan integrally formed plate 798. The plate 798 is sized to mate with thefront surface 722 of the crosshead 608. The plate 798 is secured to thefront surface 722 of the crosshead 608 using a plurality of fasteners800. When secured thereto, the elongate body 792 of the pony rod 322projects away from the crosshead 608 and is positioned along thelongitudinal axis 732 of the bore 688 formed within the crosshead guide610 and is positioned along the longitudinal axis 62 of the horizontalbore 70 formed within the fluid end section 56, as shown in FIG. 82 .The plunger connection end 794 of the pony rod 322 is configured to besecured to an end of the plunger 216 using the clamp 324. When securedtogether, the plunger 216 and pony rod 322 are aligned and both extendalong the longitudinal axes 732 and 70, as shown in FIG. 82 .

Pony Rod Seal Plate

With reference to FIGS. 86 and 124-128 , the opening of the bore 688 onthe front surface 682 of each guide 610 is sealed by the pony rod sealplate 704, as shown in FIG. 86 . The plate 704 comprises opposed frontand rear flanged portions 802 and 804 joined by an intermediate portion806 and a central passage 808 formed therein, as shown in FIGS. 124-128. The intermediate portion 806 has a greater outer diameter than thefront and rear flanged portions 802 and 804.

Continuing with FIGS. 112 and 127 , a groove 810 is formed in the outersurface of the rear flanged portion 804 for housing a seal 812, as shownin FIG. 127 . The rear flanged portion 804 is sized to be closelyreceived within the bore 688 of the guide 610, as shown in FIG. 112 .The rear flanged portion 804 is installed within the bore 688 until theintermediate portion 806 abuts the front surface 682 of the guide 610.When installed therein, the seal 812 engages the walls of the horizontalbore 688 and prevents lubricant from leaking around the plate 704.

Continuing with FIGS. 86, 110, 111, and 124-128 , the intermediateportion 806 is shaped to not interfere with the plurality of secondpassages 698 formed in the crosshead guide 610, as shown in FIG. 86 ,and comprises a plurality of passages 814. Each passage 814 ispositioned to align with one of the threaded openings 700 formed in thefront surface 682 of the guide 610. The fasteners 702 are installedwithin the aligned passages 814 and openings 700 to secure the plate 704to the guide 610, as shown in FIGS. 86 and 111 .

Continuing with FIGS. 111 and 128 , the central passage 808 comprises acounterbore 816 configured to receive a seal 818. The seal 818 is sizedto engage an outer surface of the pony rod 322 and prevent lubricantfrom leaking around the pony rod 322 during operation, as shown in FIG.111 . The seal 818 is retained within the counterbore 816 by a retainerplate 820 having a central opening 822 formed therein. The retainerplate 820 is secured to the front flanged portion 802 of the pony rodseal plate 704 using a plurality of fasteners 824, as shown in FIG. 128. The pony rod 322 is disposed within the central passage 808 of theseal plate 704 and the central opening 822 of the retainer plate 820.During operation, only the seal 818 engages the outer surface of thepony rod 322, as shown in FIG. 111 .

Operation of Crank and Crosshead Sections

With reference to FIG. 82 , during operation, rotation of the crankshaft606 causes the connecting rod 612 to pivot about the wrist pin 740 whilereciprocating along the longitudinal axis 732 of the bore 688. As theconnecting rod 612 moves, it reciprocates the crosshead 608 back andforth along the longitudinal axis 732 of the horizontal bore 688. Thus,the crankshaft 606 and the connecting rod 612 are configured totranslate rotational movement of the crankshaft 606 into linear movementof the crosshead 608. Reciprocal movement of the crosshead 608 therebycauses reciprocal movement of both the pony rod 322 and the plunger 216.

Support Plates

Turning back to FIGS. 83-86 , the power end assembly 54 furthercomprises a central support plate 830, a rear support plate 832, and aplurality of upper and lower front support plates 834 and 836. Thesupport plates 830, 832, 834, and 836 provide stability to the assembly54 as well as areas for supporting assembly of the first and second stayrods 604 and 58, as shown in FIGS. 83 and 84 .

Central Support Plate

With reference to FIGS. 129, 130, and 134 , the central support plate830 is positioned between the crosshead section 602 and the cranksection 600. The central support plate 830 is a single-integral piece oris of single-piece construction and has the same or about the sameheight and width as the crosshead and crank sections 602 and 600. Thevarious openings formed in the central support plate 830 match the size,shape, and position of the various openings formed in the rear surface684 of each crosshead guide 610.

Continuing with FIGS. 112, 129, and 130 , the central support plate 830comprises a plurality of crosshead openings 838 positioned in aside-by-side relationship. Each opening 838 corresponds with an openingof the bore 688 of each crosshead guide 610. The central support plate830 also comprises a plurality of first passages 840 and a plurality ofthreaded passages 842. The first passages 840 align with the passages638 formed in the crank frame 616 and the first passages 696 formed ineach crosshead guide 610. The aligned passages 696, 840, and 638 areconfigured to receive the plurality of first stay rods 604 in aone-to-one relationship, as shown in FIG. 112 .

Continuing with FIGS. 113 and 129 , a plurality of threaded passages 842are also formed in the central support plate 830. The threaded passages842 align with the second passages 698 formed in each crosshead guide610 and align with the bosses 640 formed on the crank frame 616. Thealigned passages 698 and 842 are configured to receive the plurality ofsecond stay rods 58 in a one-to-one relationship, as shown in FIG. 113 .

Continuing with FIGS. 111, 129, and 135 , the central support plate 830further comprises a plurality of upper and lower vent openings 844. Thevent openings 844 correspond with the vent openings 706 formed on therear surface 684 of each crosshead guide 610, as shown in FIG. 111 . Thecentral support plate 830 further comprises a plurality of dowelopenings 846. The dowel openings 846 align with dowel openings 848formed in the front surface 618 of the crank frame 616 and dowelopenings 850 formed in the rear surface 684 of each crosshead guide 610.The dowel openings 846, 848, and 850 are configured to receive alignmentdowels 852 used to properly align the components during assembly, asshown in FIG. 135 .

In alternative embodiments, screws may be used in place of some or allof the alignment dowels to retain the central support plate 830 to thecrank frame 616 until the crosshead guides 610 are installed. In suchembodiment, the corresponding dowel openings 848 are threaded so as toaccept the threaded screws.

Continuing with FIG. 130 , when the central support plate 830 is pressedagainst the crank frame 616, the seals 644 around the bosses 640 and therectangular seal 648 around each cavity 636 seal against the plate 830.Likewise, when the central support plate 830 is pressed against thecrosshead guides 610, the seals 710 around the opening of each vent 706and the seal 712 around the opening of the horizontal bore 688 sealagainst the plate 830. The seals 644, 648, 710, and 712 preventlubricant from leaking between the various components, thereby helpinglubricant to drain into the lube reservoirs 654, shown in FIG. 87 ,formed in the crank frame 616.

Rear Support Plate

Turning to FIGS. 100 and 131 , the rear support plate 832 is attached tothe rear surface 620 of the crank frame 616. The rear support plate 832is of single-piece construction and is the same or about the same heightand width as the crank frame 616. The rear support plate 832 comprises aplurality of maintenance openings 854 positioned in a side-by-siderelationship, as shown in FIG. 131 . The openings 854 correspond withthe openings of each cavity 636, shown in FIG. 89 , formed in the rearsurface 620 of the crank frame 616.

Continuing with FIGS. 100 and 131 , the rear support plate 832 furthercomprises a plurality of passages 856. The passages 856 align with thepassages 638 formed in the crank frame 616 and are configured to receivethe first stay rods 604 in a one-to-one relationship, as shown in FIG.112 . A plurality of aligned openings 858 and 860 are formed in the rearsupport plate 832 and the rear surface 620 of the crank frame 616 forreceiving fasteners 862, as shown in FIGS. 86 and 100 . The fasteners862 align and secure the rear support plate 832 to the crank frame 616during assembly.

Continuing with FIGS. 100, 103, and 135 , the rear support plate 832also comprises a plurality of threaded openings 864 surrounding eachmaintenance opening 854. The threaded openings 864 are configured toreceive a plurality of fasteners 866. The fasteners 866 are configuredto secure a cover 868 over each of the maintenance openings 854. Eachcover 868 comprises a plurality of holes 870 configured to align withthe threaded openings 864 in the rear support plate 832, as shown inFIG. 135 . The covers 868 seal the rear surface 620 of the crank frame616 from the outside environment. During operation, one or more of thecovers 868 may be removed to access the interior of the crank frame 616,if needed.

With reference to FIGS. 89 and 135 , a rectangular groove 872 forhousing a rectangular seal 874, shown in FIG. 135 , is formed aroundeach opening of each cavity 636 in the rear surface 620 of the crankframe 616, as shown in FIG. 89 . When the rear support plate 832 ispressed against the rear surface 620 of the crank frame 616, the seal874 seals against the plate 832, preventing any lubricant from leakingbetween the components.

Upper and Lower Front Support Plates

Turning to FIGS. 132-134 , each upper front support plate 834 and eachlower front support plate 836 correspond with one of the crossheadguides 610 in a one-to-one relationship. The front support plates 834and 836 provide stability to the power end assembly 54 as well as areato secure each first stay rod 604 to the assembly 54. By using aplurality of front support plates 834 and 836, only a single upper frontsupport plate 834 and a single lower front support plate 836 needs to beremoved to remove a single crosshead frame 610 from the assembly 54.

Continuing with FIGS. 112, 113, and 132 , each upper front support plate834 corresponds to the shape of the upper portion of the crosshead frame610 and comprises a first pair of openings 880. Each first opening 880aligns with the first passages 696 formed in the crosshead guide 610adjacent its upper surface 690 and is configured to receive acorresponding one of the first stay rods 604, as shown in FIG. 112 .Each upper front support plate 834 further comprises a second pair ofopenings 882. Each second opening 882 aligns with the second passages698 formed in the crosshead guide 610 between the horizontal bore 688and the upper surface 690, as shown in FIG. 113 . The second openings882 are configured to receive a corresponding one of the second stayrods 58.

Continuing with FIGS. 112, 113, and 133 , each lower front support plate836 corresponds to the shape of the lower portion of the crosshead frame610 and comprises a first pair of openings 884. Each first opening 884aligns the first passages 696 formed in the crosshead guide 610 adjacentits lower surface 692 and is configured to receive a corresponding oneof the first stay rods 604, as shown in FIG. 112 . Each lower frontsupport plate 836 further comprises a second pair of openings 886. Eachsecond opening 886 aligns with the second passages 698 formed in thecrosshead guide 610 between the horizontal bore 688 and the lowersurface 692, as shown in FIG. 113 . The second openings 886 areconfigured to receive a corresponding one of the second stay rods 58.

Continuing with FIG. 86 , while the crank frame 616 and the crossheadguides 610 may be made of ductile iron or alloy steel, the supportplates 830, 832, 834, and 836 may be made of stronger and more wearresistant materials, such as stainless steel. Reserving the heaviermaterials for the areas bearing the most load during operation helpsreduce the overall cost and weight of the assembly 54.

First Set of Stay Rods

With reference to FIGS. 112 and 135 , the power end assembly 54 isassembled by inserting each first stay rod 604 through the alignedopenings 880 or 884 and passages 696, 840, 638, and 856 formed in thefront support plates 834 or 836, crosshead guides 610, central supportplate 830, crank frame 616, and rear support plate 832, as shown in FIG.112 . Each first stay rod 604 is pushed through the aligned componentsuntil a rear end 890 of each first stay rod 604 projects from a rearsurface 892 of the rear support plate 834, and a front end 894 of eachfirst stay rod 604 projects from a front surface 896 of each frontsupport plate 834 or 836.

With reference to FIG. 136 , threads are formed on the rear end 890 ofeach first stay rod 604 for mating with a threaded blind nut 898. Theblind nut 898 is turned on the first stay rod 604 until the rear end 890bottoms out on an inner base 900 of the blind nut 898. A hole 902 isformed in the base 900 of the blind nut 898 for monitoring the positionof the first stay rod 604 during assembly and operation.

With reference to FIG. 137 , threads are formed on the front end 894 ofeach first stay rod 604 for mating with a three-piece fastener 904. Thethree-piece fastener 904 comprises a washer 906, an outer castle nut908, and an inner nut 910. The washer 906 has a flat outer surface and asplined inner surface 912. When positioned over the front end 894, aflat rear surface 914 of the washer 906 abuts the upper or lower frontsupport plates 834 or 836.

Continuing with FIG. 137 , the inner nut 910 comprises an inner threadedsurface 916 that mates with outer threads on the front end 894 of thefirst stay rod 604. The inner nut 910 further comprises a splined outersurface 918 positioned adjacent a threaded outer surface 920. Thesplined outer surface 918 mates with the splined inner surface 912 ofthe washer 906. The outer nut 908 comprises a threaded inner surface 922that mates with the threaded outer surface 920 of the inner nut 910. Aflat rear surface 924 of the outer nut 908 abuts a flat front surface926 of the washer 906.

In operation, as the outer nut 908 is turned, the inner nut 910 movesaxially away from the front support plates 834 or 836, thereby applyinga tensile load to the first stay rod 604. The engagement of the splinedsurfaces 918 and 912 between the inner nut 910 and the washer 906rotationally couples the inner nut 910 to the washer 906. Such couplingprevents the inner nut 910 from turning while providing a solid reactionpoint for turning the outer nut 908.

Continuing with FIGS. 134 and 135 , the construction of the three-piecefastener 904 allows the fastener 904 to load the first stay rods 604 intension with only a minimal amount of torsional stress. By reducing theamount of torsional stress applied to the first stay rod 604, the lifeof the stay rod 604 is increased. The construction of the three-piecefastener 904 also applies a repeatable tensile force to each first stayrod 604 when a known torque is applied to the fastener 904.

Continuing with FIGS. 112 , during assembly, the three-piece fastener904 is turned until it tightly engages the corresponding front supportplate 834 or 836 and the blind nut 898 tightly engages the rear supportplate 832, thereby securing the components of the power end assembly 54together. The various components are compressed together, therebydistributing the load applied to the assembly during operationthroughout the various components of the assembly 54. Greaterdistribution of the load during operation reduces stress to the variouscomponents, thereby increasing the lifespan of the assembly 54.

Second Set of Stay Rods

Turning to FIGS. 83 and 113 , the second set of stay rods 58 areconfigured to secure the fluid end assembly 52 to the power end assembly54. Each second stay rod 58 is inserted through the correspondingaligned opening 882 or 886 and passage 698 formed in the front supportplates 834 or 836 and the crosshead guide 610 until it reaches thethreaded passage 842 formed in the central support plate 830.

Continuing with FIG. 113 , a rear end 928 of each second stay rod 58 isthreaded and configured to thread into the threaded passage 842 formedin the central support plate 830. Each second stay rod 58 is turneduntil the rear end 928 is fully threaded within each threaded passage842 and bottoms out on the corresponding boss 640 formed in the crankframe 616. When installed therein, the front end 84 of each second stayrod 58 projects from the front surface 896 of each front support plate834 or 836, as shown in FIG. 85 .

Continuing with FIGS. 83, 85, and 113 , the sleeves 94 are installed oneach second stay rod 58 projecting from the front support plates 834 and836. Each sleeve 94 is aligned with the front support plates 834 and 836using one of the dowel sleeves 93, as shown in FIGS. 113 and 134 . Asdiscussed above, the front end 84 of each second stay rod 58 attaches tothe first section 72 of the housing 60, thereby securing each fluid endsection 56 to the power end assembly 54. Using a second set of stay rods58 to attach the fluid end assembly 52 to the power end assembly 54allows the second set of stay rods 58 to be vertically offset from thefirst set of stay rods 604. Moving the second set of stay rods 58 closerto the longitudinal axes 732 of the crosshead section 602 reduces stressand deflection between the fluid end assembly 52 and the power endassembly 54 during operation, thereby increasing the life span of theassemblies 52 and 54.

Base Section, Lubrication System, and Gearbox Section

Turning to FIGS. 138-141 , the base section 662 comprises a skidassembly 930 comprising a front beam 932 and an opposed rear beam 934joined by opposed first and second side beams 936 and 938, as shown inFIG. 139 . The side beams 936 and 938 are further joined by first andsecond crossbeams 940 and 942. The plurality of feet 660 on the lowersurface 634 of the crank frame 616 are supported on and attached to theside and rear beams 936, 938, and 934 and the second crossbeam 942 usinga plurality of fasteners 944. As will be described in more detailherein, each crosshead guide 610 is supported on the first crossbeam 940using a jack screw 946.

Continuing with FIG. 83 , during operation, the pony rods 322 andplungers 216 reciprocate over the front beam 932 of the skid assembly930. The majority of the fluid end assembly 52 is held above the groundsurface and in offset position from the skid assembly 930 by the secondstay rods 58.

Continuing with FIGS. 139 and 140 , a lubrication tank 948 is formedbetween the rear beam 934 and the second crossbeams 942. The tank 948 issealed by a cover 950. The cover 950 is secured to the inner walls ofthe tank 948 using a plurality of fasteners 952. A plurality of openings954 are formed in the tank 948 and are centrally situated along a lengthof the cover 950. Each opening 954 is situated below one of the lubereservoirs 654 formed in each cavity 636, as shown in FIG. 140 . Eachopening 954 is interconnected with the opening 658 formed in each lubereservoir 654 via a conduit 956, as shown in FIG. 140 . Duringoperation, lube draining into each lube reservoir 654 flows into thelubrication tank 948 via the conduits 956.

Continuing with FIG. 139 , the skid assembly 930 further comprises aconduit 958 attached to the second crossbeam 940 and in fluidcommunication with the lubrication tank 948. The conduit 958interconnects the lubrication tank 948 and the various hoses andconduits of the lubrication system 652 positioned on the outer surfaceof the power end assembly 54, as shown in FIG. 85 . Lubricant collectingwithin the lubrication tank 948 flows into the conduit 958 where it iseventually redirected back into the crank section 600 and the crossheadsection 602 of the assembly 54. Thus, during operation, lubricant iscontinually recycled through the assembly 54.

Continuing with FIGS. 140 and 141 , the lower surface 692 of eachcrosshead guide 610 is supported on the first crossbeam 940 by a jackscrew 946. The jack screw 946 comprises an upper support surface 960attached to a threaded nut 962. A threaded screw 964 is installed withinthe threaded nut 962 and a threaded connector 968 secured within thefirst crossbeam 940. The screw 964 is held in a desired position by ajam nut 966 engaged with the connector 968. The lower surface 692 of thecrosshead guide 610 rests on the support surface 960 of the jack screw946. The support surface 960 is raised or lowered by turning thethreaded screw 964 in a clockwise or counterclockwise direction. Whenthe support surface 960 is at the desired height, the jack screw 946 issecured in place by tightening the jam nut 966 against the connector968.

During assembly of the power end assembly 54, the space between the skidassembly 930 and the lower surface 692 of each crosshead guide 610 mayvary slightly for each guide 610. Thus, if each guide 610 were supportedon a pad of the same height, the crosshead section 602 may not be level,leading to wear or damage during operation. By supporting each crossheadguide 610 on an adjustable jack screw 946, the space between each guide610 and the skid assembly 930 can be modified, as needed, to keep thecrosshead section 602 level during operation.

Continuing with FIGS. 85, 138, and 139 , the skid assembly 930 furthercomprises a plurality of gearbox support beams 970. The gearbox supportbeams 970 project from the second side beam 938 and align with the firstside 628 of the crank frame 616. The gearbox section 678 attaches to thesupport beams 970 and the first side 628 of the crank frame 616, asshown in FIG. 85 .

With reference to FIGS. 85 and 100 , the gearbox section 678 comprisesan input shaft 664, shown in FIG. 85 , and a drive shaft 972, shown inFIG. 100 . The shafts 664 and 972 are mechanically connected via aseries of intermeshed gears supported within a gearbox 974. The driveshaft 972 is further attached to the crankshaft 606, and the input shaft664 is attached to an engine (not shown). In operation, the enginepowers rotation of the input shaft 664, which in turn rotates the driveshaft 972. Rotation of the drive shaft 972 in turn powers rotation ofthe crankshaft 606. Other components (not shown) may be installedbetween the engine and the input shaft 664 to maximize efficiency.

In alternative embodiments, the fluid end assembly described herein maycomprise one or more of the features included in the fluid end assemblydescribed in the '173 application. In further alternative embodiments,the fluid end assembly described herein may include one more embodimentsor features of the fluid ends, fluid routing plugs, or packing sealassemblies described in the following applications: U.S. patentapplication Ser. No. 17/884,712, authored by Thomas et al., and filed onAug. 10, 2022, U.S. patent application Ser. No. 17/884,736, authored bySon et al., and filed on Aug. 10, 2022, and U.S. patent application Ser.No. 17/884,757, authored by Barnett et al, and filed of Aug. 10, 2022,the entire contents of all of which are incorporated herein byreference. In even further alternative embodiments, the power endassembly described herein may comprise one or more of the featuresincluded in the power end assembly described in the '453 application.

The various features and alternative details of construction of theapparatuses described herein for the practice of the present technologywill readily occur to the skilled artisan in view of the foregoingdiscussion, and it is to be understood that even though numerouscharacteristics and advantages of various embodiments of the presenttechnology have been set forth in the foregoing description, togetherwith details of the structure and function of various embodiments of thetechnology, this detailed description is illustrative only, and changesmay be made in detail, especially in matters of structure andarrangements of parts within the principles of the present technology tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

What is claimed is:
 1. An apparatus, comprising: a modular power endassembly secured together by a plurality of first stay rods, each of theplurality of first stay rods traversing a length of the modular powerend assembly and terminating at opposed first and second ends of themodular power end assembly; and a modular fluid end assembly comprising:a variable pressure section comprising at least one suction valve; and aconstant pressure section attached to the variable pressure section andcomprising at least one discharge bore; and a plurality of second stayrods, each of the plurality of second stay rods projecting from thefirst end of the modular power end assembly and attached to the constantpressure section of the fluid end assembly.
 2. The apparatus of claim 1,in which the variable pressure section of the fluid end assembly ispositioned between the constant pressure section of the fluid endassembly and the first end of the modular power end assembly such thatthe variable pressure section is positioned adjacent the plurality ofsecond stay rods.
 3. The apparatus of claim 1, in which the plurality ofsecond stay rods comprises: a plurality of upper second stay rods; and aplurality of lower second stay rods, each lower second stay rod in aspaced-relationship with each upper second stay rod; in which thevariable pressure section of the fluid end assembly is positionedintermediate the plurality of upper second stay rods and the pluralityof lower second stay rods.
 4. The apparatus of claim 1, in which thefluid end assembly further comprises: a plurality of fluid end sectionspositioned in a side-by-side relationship, each fluid end sectioncomprising: an individual variable pressure section comprising a suctionvalve; and an individual constant pressure section attached to theindividual variable pressure section and comprising a discharge bore; inwhich the variable pressure section of the fluid end assembly comprisesa plurality of the individual variable pressure sections and the atleast one suction valve is one of the suction valves included within inone of the individual variable pressure sections; in which the constantpressure section of the fluid end assembly comprises a plurality of theindividual constant pressure sections and the at least one dischargebore is one of the discharge bores formed in one of the individualconstant pressure sections.
 5. The apparatus of claim 4, in which eachindividual constant pressure section further comprises: a first portionattached to a second portion; in which the first portion has thedischarge bore formed therein and houses at least a portion of a fluidrouting plug; in which the second portion comprises at least one suctionbore; and in which the second portion is positioned intermediate thefirst portion of the constant pressure section and the variable pressuresection.
 6. The apparatus of claim 4, in which each fluid end sectionfurther comprises: a stuffing box engaging the variable pressure sectionand housing a plunger packing and at least a portion of a reciprocatingplunger; and a retainer engaging the stuffing box and attached to thevariable pressure section using a plurality of fasteners.
 7. Theapparatus of claim 4, in which a length of each individual variablepressure section is greater than a length of each individual constantpressure section.
 8. The apparatus of claim 1, in which the modularpower end assembly comprises: a crank section comprising a crank shaft;and a crosshead section offset from the crank section and comprising aplurality of crossheads.
 9. The apparatus of claim 8, wherein themodular power end assembly further comprises: a rear support plate; anda central support plate; in which the plurality of first stay rodstraverse the rear support plate, the crank section, the central supportplate, and the crosshead section; in which the crank section is disposedbetween the rear support plate and the central support plate; in whichthe central support plate is disposed between the crosshead section andthe crank section.
 10. The apparatus of claim 9, wherein the modularpower end assembly further comprises: a plurality of front supportplates; in which the plurality of front support plates are traversed bythe plurality of first stay rods; and in which the crosshead section isdisposed between the plurality of front support plates and the centralsupport plate.
 11. The apparatus of claim 8, in which each of theplurality of crossheads comprises: a wrist pin disposed within a cavityformed in the crosshead; in which opposed ends of the wrist pin projectfrom opposed sides of the crosshead; in which the modular power endassembly further comprises: a plurality of connecting rods, eachconnecting rod interconnecting the crank shaft and a corresponding oneof the crossheads; in which each connecting rod is attached to theopposed ends of the wrist pin using a plurality of fasteners.
 12. Theapparatus of claim 8, in which each of the plurality of second stay rodstraverses the crosshead section, but not the crank section.
 13. Theapparatus of claim 8, in which the modular power end assembly furthercomprises: a central support plate positioned between the crank sectionand the crosshead section; in which each of the plurality of second stayrods is attached to the central support plate and traverses thecrosshead section, but not the crank section.
 14. The apparatus of claim1, further comprising: a sleeve disposed around each of the plurality ofsecond stay rods and interposed between the constant pressure section ofthe fluid end assembly and the first end of the modular power endassembly.
 15. The apparatus of claim 1, further comprising: an uppersuction manifold attached to the modular fluid end assembly; a lowersuction manifold attached to the modular fluid end assembly; an upperdischarge manifold attached to the modular fluid end assembly; and alower discharge manifold attached to the modular fluid end assembly. 16.The apparatus of claim 15, in which the upper and lower suctionmanifolds are attached to the fluid end assembly by a plurality ofsuction conduits; in which the upper and lower discharge manifolds areattached to the modular fluid end assembly by a plurality of dischargeconduits; and in which the plurality of suction conduits and theplurality of discharge conduits are made of a flexible material.
 17. Theapparatus of claim 1, in which the plurality of second stay rods are ina spaced-relationship with the variable pressure section of the fluidend assembly.
 18. The apparatus of claim 1, in which at least a portionof each of a plurality of a reciprocating plungers are installed withinthe variable pressure section.
 19. The apparatus of claim 1, in whichthe variable pressure section is attached to the constant pressuresection using a plurality of fasteners.
 20. The apparatus of claim 1, inwhich the constant pressure section comprises a high pressure constantpressure section joined to a low pressure constant pressure section by aplurality of fasteners; and in which the high pressure constant pressuresection comprises at least one discharge bore and the low pressureconstant pressure section comprises at least one suction bore.